Combined vaccines for prevention of porcine virus infections

ABSTRACT

The present disclosure provides vaccine compositions comprising a PRRSV vaccine and a second porcine vaccine, which are substantially free from immuno-inhibition against each other. The second porcine virus vaccine can be CSFV and/or PRV. The preparation methods for the vaccines and the formulations are also provided. The vaccine compositions provided herein confer protective immunity to pigs against porcine reproductive and respiratory syndrome, classical swine fever, and/or pseudorabies.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present applications claims priority to the following three Chinese patent applications: 201110140951.5, filed on May 27, 2011, entitled “Combination Vaccines for Porcine Reproductive and Respiratory Syndrome and Classical Swine Fever and Uses Thereof,” 201110331206.9, filed on Oct. 27, 2011, entitled “Combination Vaccines for Porcine Reproductive and Respiratory Syndrome and Porcine Pseudorabies Virus and Uses Thereof,” 201110331159.8, filed on Oct. 27, 2011, entitled “Triple Combination Vaccines for Porcine Reproductive and Respiratory Syndrome, Classical Swine Fever and Porcine Pseudorabies Virus and Preparation Methods Thereof,” which are incorporated herein by reference to their entirety.

FIELD OF THE INVENTION

The present invention relates to veterinary biological products, particularly to the live combination vaccine for preventing porcine reproductive and respiratory syndrome, classical swine fever and porcine pseudorabies virus, and preparations thereof.

BACKGROUND OF THE INVENTION

Porcine reproductive and respiratory syndrome (PRRS) is one of the major infectious diseases threatening pig industry in many places around the world. Ever since the outbreak of highly-pathogenic porcine reproductive and respiratory syndrome (also called highly-pathogenic blue ear disease) in China in 2006, PRRS has caused huge economic loss to Chinese pig industry, and is listed by Chinese Ministry of Agriculture as one of the diseases for which compulsory vaccination is required.

In addition to PRRS, pigs can be further infected by other infectious diseases such as classical swine fever (CSF) and pseudorabies. However, PRRS virus (PRRSV) is known to induce immune suppression after infecting its host, and therefore usually result in reduced immune response to secondary infections or even vaccination failure. Studies have shown that PRRSV impairs host immune system by, for example, destroying alveolar macrophages that are important for generating immune response, and/or suppressing cytokine expression that confers immunological defense to secondary infections. For example, PRRSV infection has been found to significantly inhibit host immune response to Classical Swine Fever Virus (CSFV) vaccine, even resulting in CSFV vaccination failure (Suradhat, S. et al, Vaccine, 24: 2634-3642 (2006); Li, H. et al, Veterinary Microbiology, 95: 295-301 (2003)). Co-vaccination of attenuated PRRSV and attenuated CSFV is reported to have a reduced immuno-protection rate of about 60%, which fails to meet the vaccination requirement. To vaccinate against the two pathogens, individual vaccinations separated by a 14-day interval are required (see, e.g. Du, X. Z. et al, Zhejiang Journal Animal Science and Veterinary Medicine, 2: p 5-6 (2011)). For another example, PRRSV has been found to negatively affect the vaccination effects of Pseudorabies Virus (PRV), and significantly reduce or delay the host immune response against PRV (De Bruin, M. G. M. et al, Veterinary Immunology and Immunopathology, 76(1-2): p 125-135 (2000)).

The immuno-inhibition of PRRSV tends to complicate the vaccination regimen for pigs, and reduce the vaccination efficacy and efficiency. When pigs are vaccinated against PRRSV and other viruses, it is often necessary to apply repetitive injections and multiple dosages, making the vaccination process time-consuming, labor-intensive, and costly. Moreover, in a multiple vaccination regimen, a missing dose can have a direct impact on the protection efficacy of the vaccines, while frequent and repeated vaccinations can result in immuno-paralysis, and induce immunological stress.

Therefore, there exists great need for a combined vaccine composition for PRRSV and other pig infectious diseases, without substantial immuno-inhibition.

SUMMARY OF THE INVENTION

One aspect of the present disclosure relates to vaccine compositions, comprising a Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) vaccine and a second porcine virus vaccine, wherein the PRRSV vaccine and the second vaccine are substantially free from immuno-inhibition against each other. In certain embodiments, the vaccine composition further comprises a third porcine virus vaccine, wherein the PRRSV vaccine, the second vaccine and the third vaccine are substantially free from immuno-inhibition against each other.

In certain embodiments, the second porcine virus vaccine is selected from Classical Swine Fever Virus (CSFV) vaccine and Pseudorabies Virus (PRV) vaccine. In certain embodiments, the third porcine virus vaccine is selected from Classical Swine Fever Virus (CSFV) vaccine and Pseudorabies Virus (PRV) vaccine. The second vaccine is different from the third vaccine.

In certain embodiments, the vaccine compositions comprise a PRRSV vaccine, a CSFV vaccine and a PRV vaccine, wherein the PRRSV vaccine, the CSFV vaccine and the PRV vaccine are substantially free from immuno-inhibition against each other.

In certain embodiments, the PRRSV vaccine comprises an attenuated PRRSV. In certain embodiments, the attenuated PRRSV comprises an Nsp2 nucleotide encoded by a DNA sequence which, when compared with SEQ ID NO: 4, lacks a nucleotide fragment comprising at least 50 contiguous nucleotides, wherein the fragment is at least about 80% homologous to an equal length portion of SEQ ID NO: 8. In certain embodiments, the DNA fragment comprises at least 100, at least 120, at least 150, at least 180, at least 200, at least 210, at least 220, at least 230, at least 240, at least 250, at least 260, at least 270, at least 280, at least 290, at least 300, at least 310, at least 320, at least 330, at least 340, at least 350, or at least 360 contiguous nucleotides. In certain embodiments, the DNA fragment is at least about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or 100% homologous to an equal length portion of SEQ ID NO: 8. In certain embodiments, the DNA fragment comprises SEQ ID NO: 8.

In certain embodiments, the attenuated PRRSV comprises an Nsp2 nucleotide encoding for a Nsp2 protein sequence which, when compared with SEQ ID NO: 11, lacks a peptide fragment comprising at least 20 contiguous amino acids, wherein the fragment is at least about 80% homologous to an equal length portion of SEQ ID NO: 9. In certain embodiments, the peptide fragment comprises at least 30, at least 40, at least 50, at least 60, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, at least 100, at least 105, at least 110, at least 115, or at least 120 contiguous amino acids. In certain embodiments, the peptide fragment is at least about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or 100% homologous to an equal length portion of SEQ ID NO: 9. In certain embodiments, the peptide fragment comprises SEQ ID NO: 9.

In certain embodiments, the attenuated PRRSV is attenuated from a highly-pathogenic PRRSV. In certain embodiments, the attenuated PRRSV comprises an Nsp2 nucleotide encoded by a DNA sequence which, when compared with SEQ ID NO: 5, lacks discontinuous 90 nucleotides within SEQ ID NO: 6. In certain embodiments, the Nsp2 nucleotide is encoded by a sequence having at least 90% homology to SEQ ID NO: 2. In certain embodiments, the Nsp2 nucleotide is encoded by a sequence comprising SEQ ID NO: 2.

In certain embodiments, the attenuated PRRSV further comprises an Nsp1 nucleotide sequence, which is encoded by a sequence having at least 90% homology to SEQ ID NO: 1. In certain embodiments, the attenuated PRRSV comprises an Nsp1 nucleotide sequence encoded by SEQ ID NO: 1, and an Nsp2 nucleotide sequence encoded by SEQ ID NO: 2.

In certain embodiments, the attenuated PRRSV comprises a PRRSV nucleotide sequence encoded by a sequence having at least 90% homology to SEQ ID NO: 3. In certain embodiments, the attenuated PRRSV comprises a PRRSV nucleotide sequence encoded by SEQ ID NO: 3. In certain embodiments, the attenuated PRRSV has a microorganism deposit number of CGMCC No.: 3121.

In certain embodiments, the CSFV vaccine comprises an attenuated CSFV. In certain embodiments, the attenuated CSFV is encoded by a sequence having at least 80% homology to SEQ ID NO: 10. In certain embodiments, the attenuated CSFV is encoded by SEQ ID NO: 10. In certain embodiments, the attenuated CSFV has a microorganism deposit number of CGMCC No.: 3891.

In certain embodiments, the PRV vaccine comprises an attenuated PRV. In certain embodiments, the attenuated PRV comprises a sequence having at least 80% homology to a sequence having an NCBI reference number of NC 006151.

In certain embodiments, the attenuated PRV has one or more inactivated genes selected from the group consisting of TK, PK, RR, dUTPase, gG, gC, gE, gD and gI. In certain embodiments, the attenuated PRV has an inactivated gE gene. In certain embodiments, the attenuated PRV has a microorganism deposit number of CGMCC No.: 5076.

In certain embodiments, the vaccine composition provided herein comprises an immunologically effective amount of the PRRSV vaccine, the CSFV vaccine and/or the PRV vaccine. In certain embodiments, the immunologically effective amount of the PRRSV vaccine is at least 10^(4.5) TCID₅₀, 10^(5.0) TCID₅₀, or 10^(5.5) TCID₅₀, the immunologically effective amount of the CSFV vaccine is at least 10^(0.5) FA-TCID₅₀ (fluorescent antibody—TCID₅₀), 10^(1.0) FA-TCID₅₀, 10^(1.5) FA-TCID₅₀, 10^(2.0) FA-TCID₅₀, 10^(2.5) FA-TCID₅₀, 10^(3.0) TCID₅₀, 10^(3.5) FA-TCID₅₀, 10^(4.0) FA-TCID₅₀, 10^(4.5) FA-TCID₅₀, or 10^(5.0) FA-TCID₅₀, or is at least 2.5 RID (rabbit infective dose), 3 RID, 5 RID, 10 RID, 30 RID, 100 RID, 150RID, 300 RID, 750RID, 1000 RID, 3000 RID, or 7500 RID, and/or the immunologically effective amount of the PRV vaccine is at least 10^(3.0) TCID₅₀, 10^(3.5)TCID₅₀, 10^(4.0)TCID₅₀, 10^(4.5)TCID₅₀, 10^(5.0)TCID₅₀, 10^(5.5) TCID₅₀ or 10^(6.0) TCID₅₀.

In certain embodiments, the TCID₅₀ ratio of the PRRSV vaccine to the CSFV vaccine in the combined vaccine ranges from 10000:1 to 1:1. In certain embodiments, the TCID₅₀ ratio of the PRRSV vaccine to the PRV vaccine in the combined vaccine ranges from 1:1 to 1:30. In certain embodiments, the TCID₅₀ ratio of the PRRSV vaccine:the CSFV vaccine:the PRV vaccine in the combined vaccine ranges from about 10⁴:1:10⁵ to about 5:1:6.

In certain embodiments, the vaccine compositions further comprises an adjuvant. In certain embodiments, the vaccine compositions further comprises a cryoprotectant. In certain embodiments, the cryoprotectant comprises sucrose, L-sodium glutamate, and/or lactalbumin hydrolysate.

In another aspect, the present disclosure provides methods for preparing the vaccine compositions provided herein, comprising: (a) collecting PRRSV vaccine strain, CSFV vaccine strain and/or PRV vaccine strain, which are cultivated in their respective susceptible cells, and (b) mixing two or more of the virus strains at a suitable TCID₅₀ ratio.

In certain embodiments, the susceptible cells for the PRRSV vaccine strain is a cell line selected from the group consisting of Marc-145, MA-104, Vero, and CL-2621, or a primary cell which is PAM cell. In certain embodiments, the susceptible cells for the CSFV vaccine strain is a cell line selected from the group consisting of BT, Vero, MPK, SK6, PK2a, CPK, RKC, MDBK, MDCK, CRFK, ST, and PT, or a primary cell which is BT cell. In certain embodiments, the susceptible cells for the PRV vaccine strain is a cell line selected from the group consisting of ST, PK-15, Marc-145, MDBK, BT, Vero, BHK-21, porcine kidney cell line (IBRS-2), rabbit kidney cell line (RK), and chicken embryo fibroblast cell line, or a primary cell which is porcine kidney primary cell.

In certain embodiments, the cultivation comprises inoculating each vaccine strain to its susceptible cells at a cell density ranging from 1×10⁶/ml-5×10⁶/ml in a roller bottle culture, or at a cell density ranging from 5×10⁶/ml-1×10⁷/ml in a suspension culture with an introduced adherent carrier in a bioreactor.

In certain embodiments, the PRRSV vaccine strain is inoculated at a Multiplicity of Infection (MOI) of 0.01-0.5, the CSFV vaccine strain is inoculated at a MOI of 0.1-0.5, and/or the PRV vaccine strain is inoculated at a MOI of 0.005-0.5.

In certain embodiments, the step (b) comprises mixing the collected PRRSV vaccine virus with the CSFV vaccine virus at a TCID₅₀ ratio from 10000:1 to 1:1. In certain embodiments, the step (b) comprises mixing the collected PRRSV vaccine virus with the PRV vaccine virus at a TCID₅₀ ratio from 1:1 to 1:30. In certain embodiments, the step (b) comprises mixing the collected PRRSV vaccine virus, the CSFV vaccine virus, and the PRV vaccine virus at a TCID₅₀ ratio from 10⁴:1:10⁵ to about 5:1:6.

In certain embodiments, the step (b) further comprises mixing the mixture of the collected virus solutions with a cryoprotectant. In certain embodiments, the mixture of the collected virus solutions is mixed with the cryoprotectant in a volume ratio of 75-80:25-20.

In another aspect, the present disclosure provides vaccine compositions prepared using the methods provided herein.

In another aspect, the present disclosure provides use of the vaccine compositions provided herein in the manufacture of a medicament for preventing or treating PRRS, CSF, and/or PR.

In another aspect, the present disclosure provides methods of immunizing a pig, comprising administering to the pig a vaccine composition provided herein.

In another aspect, the present disclosure provides CSFV vaccine strains, cultured in a cell line selected from the group consisting of ST, PK-15, Marc-145, MDBK, BT, Vero, BHK-21, porcine kidney cell line (IBRS-2), rabbit kidney cell line (RK), and chicken embryo fibroblast cell line, or a primary cell which is porcine kidney primary cells. In another aspect, the present disclosure provides use of these cell lines in culturing a CSFV vaccine strain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows 360 continuous nucleotides which are absent in the Nsp2 coding sequence of PRRSV TJM strain, but is present in the Nsp2 nucleotide sequence of PRRSV TJ strain.

FIG. 2 shows the 120 amino acid sequence which are absent in the Nsp2 protein as encoded by PRRSV TJM strain, but is present in the Nsp2 protein of PRRSV TJ strain.

FIG. 3 is a schematic drawing showing the 90-nucleotide deletion in the Nsp2 coding sequence of the highly-pathogenic PRRSV strain, and the 90-nucleotide deletion and the 360-nucleotide deletion in an attenuated PRRSV TJM strain.

FIG. 4 shows the discontinuous 90 nucleotide sequence which is absent in the highly-pathogenic PRRSV TJ strain, but is present in the PRRSV VR-2332 strain.

FIG. 5 shows the electrophoresis image of PRRSV TJM vaccine strain (lane 2), the highly-pathogenic PRRSV TJ virulent strain (lane 1), and water (lane 3, as negative control), respectively. M refers to the molecular weight marker.

FIG. 6 shows the electrophoresis image of PRV vaccine strain (lane 1), virulent strain (lane 2), and water (lane 3, as negative control), respectively. M refers to the molecular weight marker.

FIG. 7 shows the changes (%) in CD3+ T cells in test pigs vaccinated with PRRSV TJM single vaccine, CSFV C strain (F16) single vaccine, and combined vaccine, or negative control.

FIG. 8 shows the changes (%) in CD4+ T cells in test pigs vaccinated with PRRSV TJM single vaccine, CSFV C strain (F16) single vaccine, and combined vaccine, or negative control.

FIG. 9 shows the changes (%) in CD8+ T cells in test pigs vaccinated with PRRSV TJM single vaccine, CSFV C strain (F16) single vaccine, and combined vaccine, or negative control.

FIG. 10 shows the changes (%) in CD4+ CD8+ T cells in test pigs vaccinated with PRRSV TJM single vaccine, CSFV C strain (F16) single vaccine, combined vaccine for PRRSV and CSFV, or negative control.

FIG. 11 shows the PRRSV antibody titers (determined by ELISA) in pigs vaccinated with PRRSV TJM single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 12 shows the CSFV antibody titers (determined by ELISA) in pigs vaccinated with CSFV C strain (F16) single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 13 shows the rectal temperatures of pigs after vaccination with PRRSV TJM single vaccine, CSFV C strain (F16) single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative controls.

FIG. 14 shows the rectal temperatures of pigs after challenge with PRRSV virulent viruses, the pigs were vaccinated with PRRSV TJM single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 15 shows the rectal temperatures of pigs after challenge with CSFV virulent viruses, the pigs were vaccinated with CSFV C strain (F16) single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 16 shows the clinical symptom scores of pigs after challenge with PRRSV virulent viruses, the pigs were vaccinated with PRRSV TJM single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 17 shows the clinical symptom scores of pigs after challenge with CSFV virulent viruses, the pigs were vaccinated with CSFV C strain (F16) single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 18 shows the changes (%) in CD3+ T cells in pigs after challenge with PRRSV virulent viruses, the pigs were vaccinated with PRRSV TJM single vaccine, combined vaccine for PRRSV TJM and CSFV C strain (F16), or negative control.

FIG. 19 shows the changes (%) in CD4+ T cells after challenge with PRRSV virulent viruses.

FIG. 20 shows the changes (%) in CD8+ T cells after challenge with PRRSV virulent viruses.

FIG. 21 shows the changes (%) in CD4+ CD8+ T cells after challenge with PRRSV virulent viruses.

FIG. 22 shows the changes (%) in CD3+ T cells after challenge with CSFV virulent viruses, the pigs were vaccinated with CSFV C strain (F16) single vaccine, combined vaccine for PRRSV and CSFV, or negative control.

FIG. 23 shows the changes (%) in CD4+ T cells after challenge with CSFV virulent viruses.

FIG. 24 shows the changes (%) in CD8+ T cells after challenge with CSFV virulent viruses.

FIG. 25 shows the changes (%) in CD4+ CD8+ T cells after challenge with CSFV virulent viruses.

FIG. 26 shows the titer of anti-PRV neutralizing antibody after the vaccination with PRRSV and PRV. Group I was inoculated with PRRSV TJM single vaccine and PRV Bartha K61 single vaccine sequentially, group II was inoculated with 2-combo live vaccine, group III was inoculated with PRV Bartha K61 single vaccine, group IV was only inoculated with sterile PBS.

FIG. 27 shows the virus titers of CSFV C strain (F16) in the CSFV single vaccine and in the 2-combo vaccine (PRRSV and CSFV) after storage at 37° C. for 14 days. 200904, 200905 and 200906 represent three batches of 2-combo vaccine, and 200901, 200902 and 200903 represent three batches of PRRSV TJM single vaccine.

FIG. 28 shows the virus titers of PRRSV TJM strain in the PRRSV single vaccine and in the 2-combo vaccine (PRRSV and CSFV) after storage at 37° C. for 14 days. 200904, 200905 and 200906 represent three batches of 2-combo vaccine, and 200907, 200908 and 200909 represent three batches of CSFV C strain (F16).

FIG. 29 shows the virus titers of CSFV C strain (F16) in the CSFV single vaccine and in the 2-combo vaccine (PRRSV and CSFV) after storage at 2-8° C. for 18 months. 200904, 200905 and 200906 represent three batches of 2-combo vaccine, and 200901, 200902 and 200903 represent three batches of PRRSV TJM single vaccine.

FIG. 30 shows the virus titers of PRRSV TJM strain in the PRRSV single vaccine and in the 2-combo vaccine (PRRSV and CSFV) after storage at 2-8° C. for 18 months. 200904, 200905 and 200906 represent three batches of 2-combo vaccine, and 200907, 200908 and 200909 represent three batches of CSFV C strain (F16).

FIG. 31 shows the virus titers of PRRSV TJM strain in the 2-combo vaccine (PRRSV and PRV) after storage at 2-8° C. for 24 months. SD001, SD002 and SD003 represent three different batches of 2-combo live vaccine, respectively.

FIG. 32 shows the virus titers of PRV Bartha K61 strain in the 2-combo vaccine (PRRSV and PRV) after storage at 2-8° C. for 24 months. SD001, SD002 and SD003 represent three different batches of 2-combo live vaccine, respectively.

FIG. 33 shows the virus titers of PRRSV TJM strain in the 2-combo vaccine (PRRSV and PRV) after storage at 37° C. for 14 days. SD001, SD002 and SD003 represent three different batches of 2-combo live vaccine, respectively.

FIG. 34 shows the virus titers of PRV Bartha K61 strain in the 2-combo vaccine (PRRSV and PRV) after storage at 37° C. for 14 days. SD001, SD002 and SD003 represent three different batches of 2-combo live vaccine, respectively.

FIG. 35 shows the virus titers of PRRSV TJM strain in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 2-8° C. for 18 months. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-04, 031-05 and 031-06 represent three batches of PRRSV TJM single vaccine.

FIG. 36 shows the virus titers of CSFV C strain (F16) strain in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 2-8° C. for 18 months. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-07, 031-08 and 031-09 represent three batches of CSFV C strain (F16) single vaccine.

FIG. 37 shows the virus titers of PRV Bartha K61 strain in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 2-8° C. for 18 months. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-10, 031-11 and 031-12 represent three batches of PRV Bartha K61 single vaccine.

FIG. 38 shows the virus titers of PRRSV TJM strain in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 37° C. for 14 days. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-04, 031-05 and 031-06 represent three batches of PRRSV TJM single vaccine.

FIG. 39 shows the virus titers of CSFV C strain (F16) in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 37° C. for 14 days. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-07, 031-08 and 031-09 represent three batches of CSFV C strain (F16) single vaccine.

FIG. 40 shows the virus titers of PRV Bartha K61 strain in the 3-combo live vaccine (PRRSV TJM+CSFV C strain (F16)+PRV Bartha K61) after storage 37° C. for 14 days. 031-01, 031-02 and 031-03 represent three batches of 3-combo live vaccine, and 031-10, 031-11 and 031-12 represent three batches of PRV Bartha K61 single vaccine.

DETAILED DESCRIPTION OF THE INVENTION

The following description is merely intended to illustrate various embodiments of the present disclosure. As such, the specific modifications discussed are not intended to be limiting. It will be apparent to one skilled in the art that various equivalents, changes, and modifications may be made without departing from the spirit or scope of the subject matters presented herein, and it is understood that such equivalent embodiments are to be included herein. All publications, patents or patent applications cited herein are incorporated by reference to their entirety.

One aspect of the present disclosure relates to vaccine compositions, comprising a Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) vaccine and a second porcine virus vaccine, wherein the PRRSV vaccine and the second vaccine are substantially free from immuno-inhibition against each other.

PRRSV is a positive-strand RNA virus, for which two genotypes are currently identified: European genotype and American genotype. The genome of PRRSV contains multiple open reading frames, in which the first open reading frame (ORF1a and ORF1b) contains 80% of the sequence in the PRRSV genome, and encodes the RNA replicase which is required for PRRSV replication (Straw et al, Diseases of Swine, 9TH edition, chapter 24 (2006)). ORF1a and ORF1b are translated into a poly-protein, which is cleaved by a protease domain contained therein into several non-structural proteins, including Nsp1-Nsp12 (see, eg, Vries et al, Seminars in Virology, 8: 33-47 (1997); Allende et al, Journal of General Virology, 80: 307-315 (1999)).

The PRRSV vaccine and the second porcine virus vaccine are substantially free from immuno-inhibition against each other.

The term “substantially free from immuno-inhibition” as used herein means that, the combination two or more single vaccines does not lead to substantial reduction in protective immune response in a host to one of the single vaccines or to all of the single vaccines. The term “substantial reduction,” as used herein, refers to ≧20% reduction (e.g. ≧30%, ≧40%, ≧50%, or ≧60% reduction).

In certain embodiments, the combination of two or more single vaccines is capable of eliciting protective immune response to each of the single vaccines at a level comparable to that elicited by a single vaccine. For example, the combined PRRSV vaccine and the second porcine virus vaccine can elicit immune response to PRRSV which is at a level comparable to the immune response elicited by the PRRSV single vaccine, and/or can elicit immune response to the second porcine virus vaccine which is at a level comparable to the immune response elicited by the second porcine virus single vaccine.

The protective immune response typically includes humoral, cellular and/or mucosal immune responses, and can be characterized using methods known in the art. Humoral immune response is generated by production of antibodies (e.g. IgG) in the serum against the antigen. The antibody titers can be readily measured using assays such as ELISA (enzyme linked immunosorbent assay). For example, the virus antigen can be coated on a solid support, and then contacted with a sample suspected of containing the antibody, followed by determination of the formation of antigen-antibody complex. Cellular immune response is usually resulted from generation of cytotoxic T lymphocytes, and can be characterized through measurement of certain subpopulations of the T cells, such as CD3+ T cells, CD4+ T cells, CD8+ T cells, and CD4+CD8+ T cells, using methods such as flow cytometry. Briefly, the T cells are stained with antibodies against certain surface markers, and were sorted and quantified as different sub-populations according to the presence of the surface markers. Mucosal immune response is typically resulted from secretory IgA generated on the mucosal surfaces.

In certain embodiments, the PRRSV vaccine and the second porcine virus vaccine, when administered as a combined vaccine composition, do not substantially reduce antibody production in a host in response to the PRRSV vaccine and/or the second porcine virus vaccine.

In certain embodiments, the PRRSV vaccine and the second porcine virus vaccine, when administered as a combined vaccine composition, do not substantially reduce levels of CD3+ T cells, CD4+ T cells, CD8+ T cells, and/or CD4+CD8+ T cells in a host in response to the PRRSV vaccine and/or the second porcine virus vaccine.

In certain embodiments, the PRRSV vaccine comprises an attenuated PRRSV. In the present disclosure, “attenuated PRRSV” as used herein refers to a PRRSV that can infect a host but do not cause porcine reproductive and respiratory syndrome, or having less and/or milder symptoms. Attenuated PRRSV includes live attenuated PRRSV and its inactivated products. “Porcine reproductive and respiratory syndrome” (PRRS) as used herein refers to a series of physiological and pathological symptoms after infection of a naturally-occurring PRRSV. The symptoms include, without limitation, fever, drowsiness, anorexia, lassitude, dyspnea, cough, breeding disorder in sows, and slow growth or death in piglets, among others.

In certain embodiments, the attenuated PRRSV comprises an Nsp2 nucleotide encoded by a DNA sequence which, when compared with SEQ ID NO: 4, lacks a nucleotide fragment comprising at least 50 contiguous nucleotides, wherein the fragment is at least about 80% homologous to an equal length portion of SEQ ID NO: 8.

The term “encoded by a DNA sequence” as used herein refers to a DNA sequence that can be transcribed into a corresponding RNA sequence. A single stranded RNA virus, such as PRRSV and CSFV, has a genome which is composed of a singe strand RNA molecule that can be encoded by a DNA molecule based on Watson Crick base pairing. Such DNA molecule, when transcribed, can produce a positive-strand RNA molecule that is the identical to the RNA sequence in the virus genome.

Without being bound to theory, but it is contemplated that the absence of such nucleotide fragment in Nsp2 sequence within the portion homologous to SEQ ID NO: 8 can reduce the virulence as well as the immuno-inhibition potential of PRRSV, by, for example, producing a non-functional or less-functional Nsp2 protein, and/or negatively affecting the expression or function of other PRRSV proteins, and/or negatively affecting the life cycle of the PRRSV.

The absent fragment can be of any suitable length, as long as it can reduce the virulence as well as the immuno-inhibition of PRRSV, to the extent that is sufficient to abolish PRRSV virulence and to induce protective immunity against PRRSV without impairing immunity against other co-infected virus or vaccines. For example, the absent DNA fragment can comprise at least 100, at least 120, at least 150, at least 180, at least 200, at least 210, at least 220, at least 230, at least 240, at least 250, at least 260, at least 270, at least 280, at least 290, at least 300, at least 310, at least 320, at least 330, at least 340, at least 350, or at least 360 contiguous nucleotides. The length of the absent nucleotide fragment can also be within a range defined by any of the two values as provided above, as if these ranges have been explicitly listed herein. In certain embodiments, the absent nucleotide fragment comprises about 300 contiguous nucleotides, about 310, about 320, about 330, about 340, about 350, or about 360 contiguous nucleotides.

People of ordinary skill in the art can readily prepare recombinant viruses having various deletions in Nsp2 nucleotide sequence within the portion homologous to SEQ ID NO: 8, and test these recombinant viruses for their viability, virulence, and immuno-inhibition potential, using methods known in the art and methods provided in the present disclosure. For example, with the respect to producing and testing virulence of recombinant PRRSV containing deletions in Nsp2, methods have been described in Kim, Dal-Young et al, Virus Genes, 38: 118-128 (2009). With respect to testing immuno-inhibition of the recombinant PRRSV, methods have been described in Suradhat, S. et al, Vaccine, 24: 2634-3642 (2006), and also in Examples of the present disclosure. By deleting a fragment within the portion homologous to SEQ ID NO: 8 (e.g. deleting the 1^(st) nucleotide through the 50^(th) nucleotide in the portion, the 2^(nd) through the 60^(th) nucleotide, the 5^(th) through the 100^(th) nucleotide, etc.), one can prepare recombinant PRRSV comprising an Nsp2 nucleotide of interest, and further test the viable recombinant PRRSV strains for their abilities in forming cytopathic plaques, such that attenuated recombinant PRRSV strains can be selected and further tested in pigs for immuno-inhibition potential with respect to a second porcine virus vaccine.

In certain embodiments, the absent DNA fragment is at least about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or 100% homologous to an equal length portion of SEQ ID NO: 8. In certain embodiments, the absent DNA fragment comprises SEQ ID NO: 8. In certain embodiments, the absent DNA fragment is SEQ ID NO: 8 (see FIG. 1).

In certain embodiments, the attenuated PRRSV comprises an Nsp2 nucleotide encoding for a Nsp2 protein sequence which, when compared with SEQ ID NO: 11, lacks a peptide fragment comprising at least 20 contiguous amino acids, wherein the peptide fragment is at least about 80% homologous to an equal length portion of SEQ ID NO: 9.

The term “encoding for” as used herein means that an RNA sequence that can be translated to a corresponding amino acid sequence in accordance to the genetic codons.

Without being bound to theory, but it is contemplated that Nsp2 protein lacking such peptide fragment is less-functional or non-functional, thus impairing the virulence of the PRRSV and also reduce the immuno-inhibition on a second porcine virus vaccine.

In certain embodiments, the absent peptide fragment comprises at least 30, at least 40, at least 50, at least 60, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, at least 100, at least 105, at least 110, at least 115, or at least 120 contiguous amino acids. In certain embodiments, the absent peptide fragment is at least about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or 100% homologous to an equal length portion of SEQ ID NO: 9. In certain embodiments, the absent peptide fragment comprises SEQ ID NO: 9. In certain embodiments, the absent peptide fragment is SEQ ID NO: 9 (see FIG. 2).

The absence of the peptide fragment in Nsp2 protein can be determined through the Nsp2 nucleotide sequence. For example, the Nsp2 nucleotide can be sequenced and translated to amino acid sequence, followed by alignment with SEQ ID NO: 11 to identify the absent peptide sequence.

“Homology” or “homologous” as used herein refers to the similarity between two amino acid sequences or two nucleotide sequences. The homology between the amino acid sequences or nucleotide sequences can be calculated using any suitable methods known in the art, for example, the candidate amino acid (nucleotide) sequence can be aligned with a reference amino acid (nucleotide) sequence, introducing gaps if necessary, to achieve the maximum number of identical amino acid residues (nucleotides) between the aligned sequences, on which basis the percentage of the identical amino acid residues (nucleotides) between the two amino acid (nucleotide) sequences can be calculated. Alignment of the amino acid (or nucleotide) sequences and calculation of their homology can be achieved using the software known in the art, for example without limitation, BLAST program (available at the website of National Center of Biotechnology Information (NCBI): http://blast.ncbi.nlm.nih.gov/Blast.cgi, or see, e.g., Altschul S. F. et al, J. Mol. Biol., 215:403-410 (1990); Stephen F. et al, Nucleic Acids Res., 25:3389-3402 (1997)), ClustalW2 software (available at the website of European Bioinformatics Institute: http://www.ebi.ac.uk/Tools/msa/clustalw2/, also see, e.g., Higgins D. G. et al, Methods in Enzymology, 266:383-402 (1996); Larkin M. A. et al, Bioinformatics (Oxford, England), 23(21): 2947-8 (2007)); and TCoffee software, etc (available at the website of Sweden Bioinformatics Institute: http://tcoffrr.vital-it.vh/cgi-bin/Tcoffe/tcoffee_cgi/index.cgi, or see, e.g., Poirot O. et al, Nucleic Acids Res., 31(13): 3503-6 (2003); Notredame C. et al, J. Mol. Boil., 302(1): 205-17 (2000)). When software is used to align sequences, default parameters provided by software can be used or adjusted according to the actual situation, and these are within the scope of knowledge of an ordinary artisan in the art.

In certain embodiments, the attenuated PRRSV is attenuated from a highly-pathogenic PRRSV.

The term “highly-pathogenic PRRSV” refers to a PRRSV comprising an Nsp2 nucleotide encoded by a DNA sequence which, when compared with SEQ ID NO: 5, lacks discontinuous 90 nucleotides within the portion of SEQ ID NO: 6 (i.e. the fragment from the 1440th to the 1680th nucleotide of SEQ ID NO: 5). PRRSV isolates lacking such 90 discontinuous nucleotides (see FIG. 3) are found to have higher pathogenicity than PRRSV VR-2332 strain (see, e.g. Tian et al, PLoS ONE 2(6): e526, (2007) doi:10.1371). In certain embodiments, the discontinuous 90 nucleotides include the “TTT” from the 1440 to the 1442 nucleotide of SEQ ID NO: 5 and the sequence as shown in SEQ ID NO: 7 (see, for example, FIG. 4).

In certain embodiments, the highly-pathogenic PRRSV comprise an Nsp2 nucleotide encoded by a sequence comprising a nucleotide sequence of SED ID NO: 4 (i.e., the Nsp2 nucleotide sequence of PRRSV TJ strain). In certain embodiments, the highly-pathogenic PRRSV is PRRSV TJ strain, whose genome is encoded by a sequence having a GenBank Accession number of EU860248.

In certain embodiments, the attenuated PRRSV is attenuated from the highly-pathogenic PRRSV, and comprises an Nsp2 nucleotide sequence lacking discontinuous 90 nucleotides when compared with SEQ ID NO: 5, wherein the discontinuous 90 nucleotides are within SEQ ID NO: 6.

In certain embodiments, the Nsp2 nucleotide of the attenuated PRRSV is encoded by a sequence having at least 90% homology to SEQ ID NO: 2 (i.e. the sequence encoding Nsp2 nucleotide of PRRSV TJM strain). In certain embodiments, the Nsp2 nucleotide is encoded by a sequence comprising SEQ ID NO: 2.

In certain embodiments, the attenuated PRRSV further comprises an Nsp1 nucleotide sequence, which is encoded by a sequence having at least 90% homology to SEQ ID NO: 1 (i.e. the sequence encoding Nsp1 nucleotide of PRRSV TJM strain). In certain embodiments, the attenuated PRRSV comprises an Nsp1 nucleotide sequence encoded by SEQ ID NO: 1, and an Nsp2 nucleotide sequence encoded by SEQ ID NO: 2.

In certain embodiments, the attenuated PRRSV comprises a PRRSV nucleotide sequence encoded by a sequence having at least 90% homology to SEQ ID NO: 3 (i.e. the sequence encoding genome of PRRSV TJM strain). In certain embodiments, the attenuated PRRSV comprises a PRRSV nucleotide sequence encoded by SEQ ID NO: 3. In certain embodiments, the attenuated PRRSV has a microorganism deposit number of CGMCC No.: 3121 (such attenuated PRRSV strain is also referred to herein as PRRSV TJM strain).

The PRRSV vaccine provided herein is substantially free from immuno-inhibition against a second porcine virus vaccine. In certain embodiments, the second porcine virus vaccine is selected from Classical Swine Fever Virus (CSFV) vaccine and Pseudorabies Virus (PRV) vaccine.

Classical Swine Fever (CSF) is a highly contagious and lethal swine infectious disease caused by Classical Swine Fever Virus (CSFV). World Organization for Animal Health (OIE) has included the disease in the OIE disease list as a disease required by law to be reported. In China, classical swine fever is one of the major infectious diseases, and is listed as type I animal disease in “Category of Type I, II and III Animal Diseases.” The outbreak and prevalence of the CSF has led to the great economic loss in pig industry in China and worldwide.

Classical swine fever virus (CSFV) is classified as a member of the Pestivirus genus within the Flaviviridae family of viruses. CSFV is an enveloped positive-strand RNA virus. The virus has a genome of 12.5 kb in its full length, which comprises only one large open reading frame (ORF) that encodes a poly-protein containing approximately 4000 amino acids and with a molecular weight of about 438 kD. The poly-protein is further processed into 12 mature proteins by the viral and host proteases. All of the structural and non-structural proteins of CSFV are encoded by this large open reading frame.

An important tool to control the classical swine fever is vaccines, including inactivated vaccines and attenuated vaccines. Preparation of inactivated CSFV vaccines reached its peak in 1950-1960's, during which period formalin and crystal violet inactivated CSFV vaccines were widely used. However, they were gradually replaced by the attenuated CSFV vaccines due to their disadvantages in large dosage, short duration of immunity, slow generation of immune responses and high costs.

In certain embodiments, the CSFV vaccine is an attenuated CSFV vaccine. CSFV attenuated vaccine strains can be produced by attenuation of CSFV field strains. Reports in other countries showed that, different methods can be used to adapt CSF viruses in rabbits and to produce attenuated mutant strains. For example, three attenuated vaccine strains are widely accepted as safe and effective yet without residual pathogenicity: 1) Chinese lapinized vaccine strain (see, e.g. Qiu, H. J. et al, Scientia Agricultura Sinica, 38(8): 1675-1685 (2005)); 2) Japanese GPE(−) cell attenuated vaccine strain (see, e.g. Liu, C. et al, Chinese Journal of Animal Husbandry and Veterinary Medicine, Vol. 10, pp. 50-51 (2004)); and 3) French “Thiveosal” cold attenuated vaccine strain (see, e.g. Zhu, L. Q. et al, Chinese Veterinary Journal, 39 (2):

In certain embodiments, the attenuated CSFV vaccine is Chinese lapinized vaccine strain (C strain). The genome sequence of CSFV C strain is shown in SEQ ID NO: 10. The Chinese CSF lapinized vaccine (also called C strain), developed by Chinese scientists, has been widely used in China since 1957, and has been introduced to many other countries, where classical swine fever was brought under control or eliminated. This vaccine has been recognized as one of the most useful CSFV vaccine strains worldwide.

The CSF lapinized vaccine (C strain) can be classified according to the different methods of preparation. The first method involves preparing the vaccine in rabbits. A rabbit is inoculated with CSFV, and the lymph node, spleen or tissue is collected from the rabbit to prepare CSFV vaccine of spleen and lymph tissue origin, or CSFV vaccine of rabbit origin. This method can effectively prevent contamination of exogenous virus and ensure genetic stability of the virus. However, a lot of rabbits are required yet the quality is hard to control, and the manufacturing cost is relatively high. The second method involves using cattle or sheep primary cells or a swine cell line to produce the vaccine, i.e. CSFV vaccine of cell origin. For example, CSFV vaccine of cell origin can be prepared by passing the CSF lapinized virus (spleen origin) in cells, and performing two rounds of clonal purification by serial dilutions. This method does not require using a lot of animals. In certain embodiments, the CSFV C strain is CSFV C strain of spleen and lymph tissue origin. In certain embodiments, the CSFV C strain is CSFV C strain of cell origin, which can be derived from primary cells or a cell line.

In certain embodiments, the attenuated CSFV is encoded by a sequence having at least 80% homology to SEQ ID NO: 10 (i.e. a sequence encoding the genome of CSFV C strain). In certain embodiments, the attenuated CSFV is encoded by SEQ ID NO: 10.

In certain embodiments, the attenuated CSFV has a microorganism deposit number of CGMCC No.: 3891 (such attenuated CSFV strain is also referred to herein as CSFV C strain or F16 or CSFV C strain (F16)). CSFV C strain (F16) is CSFV C strain of cell origin.

In certain embodiments, the second porcine virus vaccine is Pseudorabies Virus (PRV) vaccine.

PRV belongs to the family of Herpesvirdae and subfamily of Alpherpesvirinae. At present, only one serotype of PRV has been identified. The genome of PRV is double-stranded DNA, having a length of about 150 kb. The virus genome is composed of a unique long (UL) region, a unique short (US) region, and terminal repeat sequences flanking the US region and internal repeat sequences. To date, 65 genes have been located in the PRV genome and most of them have been functional characterized. 56 genes have been located in the UL region, including glycoproteins such as gB, gC, gH, gK, gL, gM, gN, thymidine kinase (TK), alkaline nuclease (AN), ribonucleotide reductase (RR), DNA polymerase (POL), DBP gene, MCP gene, ICP18.5 gene and early protein 0 (EP0) and etc. The US region has been fully sequenced, in which 7 genes have been located, including: glycoprotein gD, gE, gG, gI, and protein kinase (PK) gene, 11 kd and 28 kd protein gene.

In certain embodiments, the PRV vaccine comprises an attenuated PRV. The term “attenuated PRV vaccine” refers to a PRV that is capable of infecting its host but does not cause Pseudorabies or with reduced or less severe symptoms. The attenuated PRV include live attenuated PRV and its inactivated product thereof “Pseudorabies” refers to a series of physiological and pathological symptoms caused by infection of wild type PRV. Such symptoms include, without limitation, miscarriage, stillbirth, weak foetus, mummified foetus, fever, low appetite, neurological symptoms, paralysis, system failure and even death.

In certain embodiments, the attenuated PRV comprises a sequence having at least 80% homology to a sequence having an NCBI reference number of NC 006151, for example, having at least 85%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% homology.

In certain embodiments, the attenuated PRV has one or more inactivated genes related to pathogenicity. An “inactivated” gene refers to a gene whose function is reduced or abolished due to lack or deletion of complete or partial sequences, or due to insertions or mutations in the gene. Examples of genes related to PRV pathogenicity include, without limitation, TK (for example, NCBI Gene ID: 2952559), PK (for example, NCBI Gene ID: 2952530 or 2952561), RR (for example, NCBI Gene ID: 2952535 or 2952536), dUTPase (for example, NCBI Gene ID: 2952537), gG (for example, NCBI Gene ID: 2952520), gC (for example, NCBI Gene ID: 2952505), gE (for example, NCBI Gene ID: 2952517), gD (for example, NCBI Gene ID: 2952521) and gI (for example, NCBI Gene ID: 2952516).

In certain embodiments, the attenuated PRV has one or more inactivated genes selected from the group consisting of TK, PK, RR, dUTPase, gG, gC, gE, gD and gI. In certain embodiments, the attenuated PRV has an inactivated gE gene. In certain embodiments, only gE gene is inactivated in the attenuated PRV. In certain embodiments, the attenuated PRV has an inactivated gE gene, and further has one or more inactivated genes related to pathogenicity, for example, TK, PK, RR, dUTPase, gG, gC, gD and/or gI.

The attenuated PRV vaccine can be obtained using methods known in the art. For example, an isolate of PRV wild type strain can be attenuated by passaging the virus in non-porcine cells or in egg embryos, or by culturing under an elevated temperature and/or in the presence of a mutagen. Many attenuated PRV vaccines are known in the art, for example, Bartha K61 strain (see, for example, Bartha, A. Experiments to reduce the virulence of Aujeszky's virus. Magyar allatorvosok lapja 16, 42-45 (1961)), BUK strain, NIA4 strain, Alfort strain, and VGNKI strain etc. These attenuated PRV vaccines can be used in the present disclosure. For example, the wild type or attenuated PRV strain may further be modified, such that one or more target genes related to pathogenicity are inactived yet the virus is still capable of replication. Many attenuated PRV vaccines obtained by genetic engineering are known in the art, for example, PRV-BUK-d13 strain (see, for example, Kit S. et al, Am. J. Vet. Res., 1985, 46 (6): 1359-1367), PRV dlgC/dlTK strain (see, for example, Kit S. et al, Am. J. Vet. Res., 1987, 48 (5): 780-793), S—PRV-002 (see, for example, U.S. Pat. No. 4,514,497), PRV783 strain (see, for example, Van Oirschot J T et al, Am. J. Vet. Res., 1984, 45 (10): 2099-2103), EL-001, and PRV376 etc.

In certain embodiments, the attenuated PRV lacks gE gene. In certain embodiments, the attenuated PRV has a microorganism deposit number of CGMCC No.: 5076 (such attenuated PRV strain is also referred to as PRV Bartha K61 strain herein).

In certain embodiments, the attenuated PRV further comprises one or more inactivated genes that do not affect viral replication or host infection. In certain embodiments, the attenuated PRV further comprises one or more heterogeneous genes that are not present in PRV genome. The inserted heterogeneous genes are useful in detection and/or diagnosis of the vaccines.

In certain embodiments, the vaccine composition further comprises a third porcine vaccine, wherein the PRRSV vaccine, the second porcine virus vaccine and the third porcine virus vaccine are substantially free from immuno-inhibition against each other. In certain embodiments, the third porcine vaccine can be selected from a CSFV vaccine and a PRV vaccine, provided that the second vaccine is different from the third vaccine.

In certain embodiments, the vaccine compositions comprise a PRRSV vaccine, a CSFV vaccine and a PRV vaccine, wherein the PRRSV vaccine, the CSFV vaccine and the PRV vaccine are substantially free from immuno-inhibition against each other. The three vaccines, when combined in a vaccine composition, do not substantially reduce antibody production and/or T cell subpopulation levels in a host in response to the PRRSV vaccine, the CSFV vaccine and/or the PRV vaccine. In certain embodiments, the PRRSV vaccine comprises PRRSV TJM strain. The CSFV vaccine comprises any of the attenuated CSFV provided herein, including but not limited to, CSFV C strain. The PRV vaccine comprises any of the attenuated PRV strain provided herein, for example but not limited to, PRV Bartha K61 strain.

In certain embodiments, the present disclosure provides a vaccine composition, comprising PRRSV TJM strain having a microorganism deposit No. of CGMCC NO. 3121, and CSFV C strain. In certain embodiments, the CSFV C strain is CSFV F16 having a microorganism deposit No. of CGMCC NO. 3891. PRRSV TJM strain and CSFV C strain (F16) do not show any immuno-inhibition or immune suppression against each other. Both vaccine strains have good safety, immunogenicity and specificity, and can provide effective protection against both the highly-pathogenic porcine reproductive and respiratory syndrome and classical swine fever, which are two of the major epidemics in pig herds.

In certain embodiments, the present disclosure provides a vaccine composition, comprising PRRSV TJM strain having a microorganism deposit No. of CGMCC NO. 3121, and PRV Bartha K61 strain with microorganism deposit No. of CGMCC NO. 5076. PRRSV TJM strain and PRV Bartha K61 strain do not show any immuno-inhibition or immune suppression between each other. Both vaccine strains have good safety, immunogenicity and specificity, and can provide effective protection against both the highly-pathogenic porcine reproductive and respiratory syndrome and pseudorabies, which are two of the major epidemics in pig herds.

In certain embodiments, the present disclosure provides a vaccine composition, comprising PRRSV TJM strain, CSFV C strain (F16) and PRV Bartha K61 strain. PRRSV TJM strain, CSFV C strain (F16) and PRV Bartha K61 strain do not show any immuno-inhibition or immune suppression among each other. The three vaccine strains have good safety, immunogenicity and specificity, and can provide effective protection against the highly-pathogenic porcine reproductive and respiratory syndrome, classical swine fever and pseudorabies, which are three of the major epidemics in pig herds.

The detailed deposit information of PRRSV TJM strain is as follows: Microorganism Deposit No.: CGMCC No. 3121; Taxonomic Name: Porcine Reproductive and Respiratory Syndrome Virus; Deposit Address: Institute of Microbiology, Chinese Academy of Sciences, NO. 1 West Beichen Road, Chaoyang District, Beijing, China; Deposit Unit: China General Microbiological Culture Collection Center; and Deposit Date: Jun. 15, 2009.

The detailed deposit information of CSFV C strain (F16) is as follows: Microorganism Deposit No.: CGMCC No. 3891; Taxonomic Name:; Classical Swine Fever Virus; Deposit Address: Institute of Microbiology, Chinese Academy of Sciences, NO. 1 West Beichen Road, Chaoyang District, Beijing, China; Deposit Unit: China General Microbiological Culture Collection Center; and Deposit Date: May 27, 2010.

The detailed deposit information of PRV Bartha K61 strain is as follows: Microorganism Deposit No.: CGMCC No. 5076; Taxonomic Name: Pseudorabies Virus; Deposit Address: Institute of Microbiology, Chinese Academy of Sciences, NO. 1 West Beichen Road, Chaoyang District, Beijing, China; Deposit Unit: China General Microbiological Culture Collection Center; and Deposit Date: Jul. 21, 2011.

In certain embodiments, the vaccine composition provided herein comprises an immunologically effective amount of PRRSV vaccine, CSFV vaccine and/or PRV vaccine. The term “immunologically effective amount” as used herein, refers to an amount of a vaccine that is sufficient to induce a protective immune response in the host against the intended antigen or pathogen. For example, an immunologically effective amount may be sufficient to reduce or delay the onset of one or more symptoms of the infection, reduce morbidity and/or mortality of the infected host, induce a sufficient level of antibodies against the pathogen, increase levels of T cell sub-populations, and any combinations thereof. Characterization and/or quantification of the protective immune response can be carried out using methods known in the art, for example, by measuring antibody titers against the pathogen, and/or amount of T cell subpopulations, as described above, or by observing for clinical manifestations of the vaccinated pigs after virulent virus challenge.

The immunologically effective amount of a virus vaccine can be characterized in virus titer, for example, in 50% tissue culture infective dose (TCID₅₀). In certain embodiments, the immunologically effective amount of the PRRSV vaccine is at least 10^(3.0) TCID₅₀, 10^(3.5) TCID₅₀, 10^(4.0) TCID₅₀, 10^(4.5) TCID₅₀, 10^(5.0) TCID₅₀, or 10^(5.5) TCID₅₀. In certain embodiments, the immunologically effective amount of the PRRSV vaccine is at least 10^(4.5) TCID₅₀, at least 10^(5.0) TCID₅₀ or at least 10^(5.5) TCID₅₀. In certain embodiments, the vaccine compositions provided herein comprises about 10^(4.5) TCID₅₀ to about 10^(6.0) TCID₅₀, or about 10^(5.0) TCID₅₀ to about 10^(6.0) TCID₅₀ of the PRRSV vaccine.

In certain embodiments, the immunologically effective amount of the CSFV vaccine is at least 10^(0.5) FA-TCID₅₀ (fluorescent antibody—TCID₅₀), 10^(1.0) FA-TCID₅₀, 10^(1.5) FA-TCID₅₀, 10^(2.0) FA-TCID₅₀, 10^(2.5) FA-TCID₅₀, 10^(3.0) FA-TCID₅₀, 10^(3.5) FA-TCID₅₀, 10^(4.0) FA-TCID₅₀, 10^(4.5) FA-TCID₅₀, or 10^(5.0) FA-TCID₅₀. In certain embodiments, the immunologically effective amount of the CSFV vaccine is at least 10^(4.0) FA-TCID₅₀/ml. In certain embodiments, the vaccine compositions provided herein comprises about 10^(0.5) FA-TCID₅₀ to about 10^(5.0) FA-TCID₅₀, or about 10^(4.0) FA-TCID₅₀ to about 10^(5.0) FA-TCID₅₀ of the CSFV vaccine. The term “FA-TCID50” refers to a TCID₅₀ value determined by a method based on fluorescent antibody.

In certain embodiments, the immunologically effective amount of the CSFV vaccine is at least 2.5 RID, 3 RID, 5 RID, 10 RID, 30 RID, 100 RID, 150RID, 300 RID, 750 RID, 1000 RID, 3000 RID, or 7500 RID.

In certain embodiments, the immunologically effective amount of the PRV vaccine is at least 10^(3.0) TCID₅₀, 10^(3.5) TCID₅₀, 10^(4.0) TCID₅₀, 10^(4.5) TCID₅₀, 10^(5.0) TCID₅₀, 10^(5.5) TCID₅₀ or 10^(6.0) TCID₅₀. In certain embodiments, the immunologically effective amount of the PRV vaccine is at least 10^(5.5) TCID₅₀, or at least 10^(6.0) TCID₅₀. In certain embodiments, the vaccine compositions provided herein comprises about 10^(5.0) TCID₅₀ to about 10^(6.5) TCID₅₀, or about 10^(5.5) TCID₅₀ to about 10^(6.5) TCID₅₀ of the PRV vaccine.

The TCID₅₀ of a virus vaccine can be determined using any suitable methods known in the art. For example, the virus vaccine (PRRSV vaccine and/or PRV vaccine) can be prepared as a virus solution, and 10-fold serial dilutions of the virus solution can be prepared and inoculated to a 96-well culture plate seeded with susceptible cells. Virus solutions of each dilution can be inoculated in 8 wells at 100 ul/well. The plates can be placed in an incubator at 37° C., with 5% CO₂, and cultured for 4-5 days. The cells are observed for cytopathic effects, and TCID₅₀ is calculated as the virus concentration at which 50% of the tissue culture shows cytopathic effects. A detailed description of the method can be found at Reed L J, Muench H, A simple method of estimating fifty percent end points. Am J Hyg 1938; 27:493-97.

CSFV is a virus that does not cause obvious cytopathic effects, and the TCID₅₀ is therefore determined by immunofluorescent method, or with rabbit infection study. In certain embodiments, the FA-TCID₅₀ for the CSFV vaccine is determined by an immunofluorescent method. Briefly, the CSFV vaccine strain is prepared as a solution containing 1 dose/ml, and 10-fold serial dilutions are prepared with DMEM culture medium supplemented with 3.5% serum. Dilutions containing 10⁻¹, 10⁻², 10⁻³, 10⁻⁴, and 10⁻⁵ of original virus samples are inoculated respectively to single layer of BT cells at 0.1 ml/well. After 3-4 days culture, the cells are fixed and contacted with a fluorescent monoclonal antibody of CSFV (for direct immunofluoresenct method). After 45-60 minutes reaction, the cells are observed for presence of fluorescence, which indicates for presence of virus. Alternatively, the fixed cells can be contacted with an unlabelled monoclonal antibody of CSFV (for indirect immunofluoresenct method), and after 45-60 minutes reaction, the cells are reacted with fluorescence-labeled secondary antibody for another 45-60 minutes. The cells are observed for presence of fluorescence which indicates the presence of the virus. FA-TCID50 is calculated in accordance with the Reed-Muench method (see, e.g Reed L J, Muench H, A simple method of estimating fifty percent end points. Am J Hyg 1938; 27:493-97).

In certain embodiments, the amount of the CSFV vaccine is determined by rabbit infectivity dose. Briefly, the CSFV vaccine strain is prepared as a solution containing 1 dose, and is then diluted 7500-fold to prepare the testing sample. 2 rabbits of 1.5-3 kg body weight are each injected with 1 ml testing sample, and body temperature is taken twice each day for the first 48 hours, and once every 6 hours thereafter. The body temperature reactions are monitored and graded according the below criteria: 1) typical fever reaction (++): the latency period is about 48-96 hours, the body temperature significantly rises, in which at least 3 temperatures rise beyond the normal temperature by at least 1° C. and last for 18-36 hours; 2) slightly fever reaction (+): the latency period is about 48-96 hours, the body temperature significantly rises, in which at least 2 temperatures rise beyond the normal temperature by at least 0.5° C. and last for 12-36 hours; 3) suspected fever reaction (±): the latency period is about 48-96 hours, the body temperature fluctuates, the elevated temperature lasts for less than 12 hours, or the latency period is at least 24 hours, and fever reaction is demonstrated within 48 hours, or after 96 to 120 hours; and 4) no fever reaction (−): body temperature is normal. The vaccine is determined as having an amount of 7500 RID, if the two testing rabbits both showed typical fever reaction (++), or one of the rabbits showed typical fever reaction (++) while the other showed slightly fever reaction (+). In case the rabbits showed other reactions that are difficult to characterize, the test can be repeated, but should not be repeated for more than 3 times.

The single virus vaccines can be mixed at a suitable ratio to provide the vaccine compositions described herein. For example, a single virus vaccine can be prepared as a virus solution containing the vaccine strain at a certain virus titer (e.g. a certain TCID₅₀), and two or more single virus vaccines are mixed at a suitable ratio to give a combination vaccine containing each single vaccine at a predetermined amount (e.g. TCID₅₀) or ratio.

In certain embodiments, in a combined vaccine composition comprising the PRRSV vaccine and the CSFV vaccine, the TCID₅₀ ratio of the PRRSV vaccine to the CSFV vaccine ranges from 10000:1 to 1:1, 1000:1 to 1:1, 100:1 to 1:1, 10:1 to 1:1, or 5:1 to 1:1. For example, the vaccine composition can comprise 10^(4.5) TCID50 of PRRSV vaccine, and 10^(0.5) FA-TCID50 of CSFV vaccine, or 10^(4.5) TCID50 of PRRSV vaccine, and 10^(3.5) FA-TCID50 of CSFV vaccine, or 10^(5.0) TCID50 of PRRSV vaccine, and 10^(4.0) FA-TCID50 of CSFV vaccine.

In certain embodiments, in a combined vaccine composition comprising the PRRSV vaccine and the PRV vaccine, the TCID₅₀ ratio of the PRRSV vaccine to the PRV vaccine ranges from 1:1 to 1:30, 1:1 to 1:25, 1:1 to 1:20, 1:1 to 1:15, 1:1 to 1:10, 1:1 to 1:9, 1:1 to 1:8, 1:1 to 1:7, 1:1 to 1:6, 1:1 to 1:5, 1:2 to 1:10, 1:3 to 1:10, 1:4 to 1:10, or 1:5 to 1:10. For example, the vaccine composition can comprise 10^(4.5) TCID50 of PRRSV vaccine, and 10^(5.5) TCID50 of PRV vaccine, or 10^(5.0) TCID50 of PRRSV vaccine, and 10^(5.5) TCID50 of PRV vaccine, or 10^(5.0) TCID50 of PRRSV vaccine, and 10^(6.5) TCID50 of PRV vaccine.

In certain embodiments, in a combined vaccine composition comprising the PRRSV vaccine, the CSFV vaccine and the PRV vaccine, the TCID₅₀ ratio of the PRRSV vaccine:the CSFV vaccine:the PRV vaccine is about 10⁴:1:10⁵ to about 5:1:6. For example, the vaccine composition can comprise 10^(4.5) TCID50 of PRRSV vaccine, 10^(0.5) FA-TCID50 of CSFV vaccine and 10^(5.5) TCID50 of PRV vaccine. For another example, the vaccine composition can comprise 10^(4.5) TCID50 of PRRSV vaccine, 10^(4.0) FA-TCID50 of CSFV vaccine and 10^(5.5) TCID50 of PRV vaccine. For another example, the vaccine composition can comprise 10^(5.7) TCID50 of PRRSV vaccine, 10^(5.0) FA-TCID50 of CSFV vaccine and 10^(5.8) TCID50 of PRV vaccine. For another example, the vaccine composition can comprise 10^(6.0) TCID50 of PRRSV vaccine, 10^(5.0) FA-TCID50 of CSFV vaccine and 10^(6.5) TCID50 of PRV vaccine.

The vaccine compositions provided herein can further comprise an adjuvant. The adjuvant can protect the vaccine from in vivo degradation, and/or can non-specifically stimulate the immune system, thereby can be helpful to enhance the immunological response to the vaccine. Examples of adjuvants include, without limitation, mineral salts (e.g., aluminum hydroxide, aluminum phosphate, calcium hydroxide), water-in-oil emulsion (e.g., complete Freund's adjuvant, incomplete Freund's adjuvant, etc.), saponin adjuvants (e.g., Stimulon™, etc), derivatives of bacteria or micro-organisms (e.g., LPS, lipid A derivatives, etc) and micro-particles (e.g., poly-α-hydroxyacid, etc).

The vaccine composition provided herein can further comprise a cryoprotectant. The cryoprotectant can keep the biological products in good stability and reduce the damage to the biological activity of the vaccine during the process of lyophilization. Examples of the cryoprotectant include sucrose, L-sodium glutamate or lactalbumin hydrolysate, etc.

Methods for Preparation

In another aspect, the present disclosure provides methods for preparing the vaccine compositions provided herein, comprising: (a) collecting PRRSV vaccine strain, CSFV vaccine strain and/or PRV vaccine strain, which are cultivated in their respective susceptible cells, and (b) mixing two or more of the virus strains at a suitable TCID₅₀ ratio.

In certain embodiments, the step (a) comprises: inoculating the PRRSV vaccine strain, CSFV vaccine strain and/or PRV vaccine strain to their respective susceptible cells, culturing the cells to prepare seed viruses for vaccine production, inoculating the seed viruses to their respective susceptible cells, propagating the cells to obtain antigen solutions containing the respective viruses.

In certain embodiments, the PRRSV vaccine strain is an attenuated vaccine strain of the highly-pathogenic PRRSV. In certain embodiments, the PRRSV vaccine strain is PRRSV TJM strain.

In certain embodiments, the CSFV vaccine strain is an attenuated CSFV. In certain embodiments, the CSFV vaccine strain is CSFV C strain (F16).

In certain embodiments, the PRV vaccine strain is an attenuated PRV. In certain embodiments, the PRV vaccine strain is Bartha K61 strain.

In certain embodiments, the susceptible cells for the PRRSV vaccine strain include, without limitation, cell lines such as Marc-145 cell line, MA-104 cell line, Vero cell line or CL-2621 cell line, or primary cells such as PAM cells.

In certain embodiments, the susceptible cells for the CSFV vaccine strain include, without limitation, cell lines such as BT cell line, Vero cell line, MPK cell line, SK6 cell line, PK2a cell line, CPK cell line, RKC cell line, MDBK cell line, MDCK cell line, CRFK cell line, PT cell line and ST cell line, or primary cells such as BT cells. Both PT cell line and ST cell line are pig testis cell lines.

In certain embodiments, the susceptible cells for the PRV vaccine strain include, without limitation, passaging cell lines such as ST cell line (ATCC No.: CRL-1746), PK-15 cell line (ATCC No.: CCL-33), Marc-145 cell line (ATCC No.: CRL-12219), bovine kidney MDBK cell line (ATCC No.: CCL-22), bovine turbinate BT cell line (ATCC No.: CRL-1390), Vero cell line (ATCC No.: CCL-81), BHK-21 cell line (ATCC No.: CCL-10), pig kidney cell line (see, IBRS-2, e.g., DECASTRO, M. P. 1964. Behavior of foot and mouth disease virus in cell culture: susceptibility of the IB-RS-2 swine cell line. Arquivos Instituto Biologica 31: 63-78), and rabbit kidney RK cell line (ATCC No.: CCL-106); or primary cells such as chicken embryo fibroblast cells and pig kidney cells. Primary cells can be prepared using methods known in the art, for example by isolating tissues from animal and preparing cells.

In certain embodiments, the susceptible cells were cultured preferably at 33-37° C., in the presence of 5% CO₂. The methods of culturing the susceptible cells can comprise: passaging the cell line after digestion with EDTA-trypsin solution, continuing to cultivate the cell line in growth medium, when cells reach 90-100% confluence, they can be further passaged or inoculated with a seed virus. The method for cultivating the cell line is preferably any of the following: cultivating the cells in a roller bottle and allowing the cell density to reach 1×10⁶/ml-5×10⁶/ml; or introducing an adherent carrier to a bioreactor for suspension cultivation and allowing the cell density to reach 5×10⁶/ml-1×10⁷/ml, wherein the adherent carrier is preferably a microcarrier or paper.

In certain embodiments, the PRRSV vaccine strain is inoculated to its susceptible cells at a Multiplicity of Infection (MOI) of 0.01-0.5, the CSFV vaccine strain is inoculated to its susceptible cells at a MOI of 0.1-0.5, or the inoculation amount is 3%-5% virus of cell origin, and/or the PRV vaccine strain is inoculated to its susceptible cells at a MOI of 0.005-0.5.

In certain embodiments, the cells inoculated with the respective virus vaccine strain are cultivated for 3-5 days after the inoculation, and seed viruses for vaccine production can be harvested. For PRRSV strain, the seed virus is harvested when the cytopathic effect reaches 70%. For CSFV strain, the first harvest is performed by medium change at the 5^(th) day after the inoculation, and subsequent harvests are performed by medium change at 4-day intervals, provided that no more than five harvests are performed. For PRV strain, the cell culture medium containing the virus is harvested 2-3 days after the inoculation.

In certain embodiments, the seed virus for vaccine production has a suitable virus titer. For example, the seed virus for PRRSV TJM strain can be no less than 10^(7.0)TCID₅₀ virus per ml, the seed virus for CSFV C strain (F16) can be >100,000 rabbit infective dose per ml or no less than 10^(6.0) FA-TCID₅₀ virus per ml as measured by an immunofluorescence based assay, and/or the seed virus for PRV Bartha K61 strain can be no less than 10^(8.0)TCID₅₀ virus per ml.

In certain embodiments, the seed viruses are inoculated to their respective susceptible cells, and are propagated to obtain antigen solutions containing the respective viruses. In certain embodiments, the antigen solutions as obtained has a suitable virus content, for example, no less than 10^(7.0)TCID₅₀ virus per ml for the PRRSV TJM strain, >100,000 RID per ml or no less than 10^(6.0) FA-TCID₅₀ virus per ml as measured by an immunofluorescence-based assay for the CSFV C strain (F16), and/or no less than 10^(8.0)TCID₅₀ virus per ml for PRV Bartha K61 strain.

In certain embodiments, the step (b) comprises mixing the collected the PRRSV vaccine strain and the CSFV vaccine strain at a TCID₅₀ ratio from 10000:1 to 1:1. In certain embodiments, the step (b) comprises mixing the collected PRRSV vaccine virus with the PRV vaccine virus at a TCID₅₀ ratio from 1:1 to 1:30. In certain embodiments, the step (b) comprises mixing the collected PRRSV vaccine virus, the CSFV vaccine virus, and the PRV vaccine virus at a TCID₅₀ ratio of about 10⁴:1:10⁵ to about 5:1:6.

In certain embodiments, the step (b) further comprises mixing the mixture of the collected virus solutions with a cryoprotectant. In certain embodiments, the mixture of the collected virus solutions is mixed with the cryoprotectant in a volume ratio of 75-80:25-20.

In another aspect, the present disclosure provides vaccine compositions prepared using the methods provided herein.

In another aspect, the present disclosure provides use of the vaccine compositions provided herein in the manufacture of a medicament for preventing or treating PRRS, CSF, and/or PR.

In another aspect, the present disclosure provides methods of immunizing a pig, comprising administering to the pig a vaccine composition provided herein.

In another aspect, the present disclosure provides CSFV vaccine strains, cultured in a cell line selected from the group consisting of ST, PK-15, Marc-145, MDBK, BT, Vero, BHK-21, porcine kidney cell line (IBRS-2), rabbit kidney cell line (RK), and chicken embryo fibroblast cell line, or a primary cell which is porcine kidney primary cells. In another aspect, the present disclosure provides use of these cell lines in culturing a CSFV vaccine strain.

The present disclosure also provides a vaccine composition prepared using the preparation method described above, comprising a PRRSV vaccine and a CSFV vaccine.

The present disclosure also provides uses of the vaccine composition in manufacturing a biological product for preventing or treating porcine reproductive and respiratory syndrome and classical swine fever.

The combination vaccine provided herein shows significant efficacy in preventing highly-pathogenic porcine reproductive and respiratory syndrome and classical swine fever. The highly-pathogenic PRRSV strains and CSFV vaccine strains provided herein do not show any immunological suppression, and the combination vaccines prepared therefrom show no difference from each of their monovalent vaccines in terms of safety, immunogenicity, duration of immunity, immunological protection, and stability. The results of safety study show that, animals which received single dose, repetitive doses, over-dose inoculation of the vaccine show normal body temperature and spirit without any clinical symptoms. The results of efficacy study show that, the vaccine provided herein can provide significant protection to animals against the challenge of virulent strains of high pathogenic PRRSV and CSFV, and can effectively prevent infection of high pathogenic PRRSV and CSFV. The results of immunity duration study show that, the duration of immunity lasts for 6 months, which can ensure effective protection to pigs during the immunity period. The results of stability study show that, the vaccine can be stored at 2-8° C. for 18 months, which indicates its advantage in long shelf life and stable storage. The vaccines provided herein can be used to inoculate animals and prevent two diseases with one injection, thereby reduce the work load of vaccination and the immunization frequency, minimize the stress to the pig herds, and prevent immune tolerant and failure caused by frequent vaccination.

The present disclosure also provides a method for immunizing a pig, comprising administering the vaccine composition provided herein to the pig. The pigs can be immunized by, for example, injection. The immunization can be one single administration or repetitive administration of multiple doses. The methods for immunization or dosages can be adjusted by an experienced veterinary professional according to the actual conditions.

EXAMPLES

The following examples are intended to further illustrate the present inventions. The advantages and features of the present invention will become clear with the descriptions. However, these illustrations are merely exemplary, and should not be construed as limitations to the scope of the present disclosure.

General

Inoculation of vaccines was performed by injection into the neck muscle of the pigs. Virus challenge was performed by dripping the virus to the nose of the test pigs, and/or injecting the virus to the muscle of the test pigs. The FA-TCID₅₀ of CSFV virus amount was measured by immunofluorescence-based method.

FACS assay for T cells. The T cells were measured by flowcytometry method. Briefly, the blood samples were treated with anti-coagulant, followed by lysis of red blood cells. The treated samples were stained with FITC-CD8 monoclonal antibody (mAb), PE-CD4 mAb, PECy5-CD3 mAb, respectively (all antibodies were purchased from 51AB Biotech, Beijing). After 45-min incubation, the unreacted antibodies were removed, and the cells were suspended with PBS and analyzed on flow cytometer (BD FACSAria).

ELISA assay. The antibodies against PRRSV antigens, antibodies against CSFV antigens were measured by ELISA, using the respective detection kits purchased from Beijing IDEXX Yuanheng Laboratories Co., Ltd.

Part I: Preparation of the Vaccines

Example 1 Preparation of PRRSV Vaccines

Cell Passage and Culture

Marc-145 cells, which were used to culture the PRRSV vaccine strain TJM, were trypsinized and divided in 1:3. The cells were cultured at 37° C. in culture medium. After the cells formed a single layer, they were passaged or inoculated with a virus strain.

Propagation of the Seed Viruses in Cells

The vaccine strain TJM for highly virulent PRRSV was inoculated to Marc-145 cells in a MOI of 0.01-0.5. The inoculated cells were cultured for 3-5 days, and the virus solution was collected when the cytopathic effects (CPE) reached 70%. The collected virus solution was used as the seed virus of PRRSV TJM strain.

The seed virus was characterized according to Veterinary Pharmacopoeia of People's Republic of China. The seed virus was absent for bacteria, mold, or mycoplasma. The PRRSV seed virus solutions did not show adverse effects to pigs. The seed virus solution of PRRSV TJM strain contained no less than 10^(7.0)TCID₅₀ virus per 1 ml.

Propagation of the Virus Solution for Vaccine Production

Marc-145 cells were cultured to 90-100% confluent single layer. Cell culture medium was discarded, and cells were washed twice with PBS. The seed virus solution of PRRSV TJM strain was inoculated at MOI of 0.01-0.5. The inoculated cells were cultured for 3-5 days, and the virus solution was collected when the CPE reached 70%. The collected virus solution was used as the virus solution for vaccine production. Such virus solution was characterized, and was absent for bacteria, mold, or mycoplasma, and the virus solution of PRRSV TJM strain contained no less than 10^(7.0)TCID₅₀ virus per 1 ml. The virus solution was diluted appropriately to prepare PRRSV single vaccine, or mixed with other vaccines to prepare combined vaccines.

Example 2 Preparation of CSFV Vaccines

Cell Passage and Culture

The BT cells, which were used to culture the CSFV vaccine strain, were trypsinized and divided in 1:5. The cells were cultured at 37° C. in culture medium. After the cells formed a single layer, they were passaged or inoculated with a virus strain.

The CSFV C strain (F16) was prepared into a 0.3% virus solution, and was inoculated to a single layer of BT cells. The inoculated cells were cultured for 5 days, and the virus solution is collected as the seed virus of CSFV vaccine strain.

Characterization of the Seed Viruses

The seed viruses were characterized according to Veterinary Pharmacopoeia of People's Republic of China. The seed viruses were absent for bacteria, mold, or mycoplasma. The CSFV C strain (F16) were tested as a qualified seed virus solution, and showed no adverse effects to pigs. The seed virus solution of CSFV C strain (F16) contained >100,000 rabbit infective dose (RID), or no less than 10^(6.0) FA-TCID₅₀ virus per 1 ml virus solution as measured by an immunofluorescence-based method.

Propagation of the Virus Solution for Vaccine Production

BT cells were cultured to 90-100% confluent single layer. Cell culture medium was discarded, and cells were washed twice with PBS. The seed virus solution of CSFV C strain (F16) was inoculated at MOI of 0.1-0.5 or at an amount of 3%-5%. At the 5^(th) day after the inoculation, the first harvest is performed by medium change, and the subsequent harvests are performed at 4-day intervals, provided that no more than 5 harvests are performed. The virus solutions as collected were stored under −20° C. and used as the virus solution for vaccine production. Such virus solution was characterized, and the seed virus solution of CSFV C strain (F16) contained >100,000 RID, or no less than 10^(6.0) FA-TCID₅₀ virus per 1 ml virus solution as measured by an immunofluorescence-based method. The virus solution was diluted appropriately to prepare CSFV single vaccine, or mixed with other vaccines to prepare combined vaccines.

Example 3 Preparation of PRV Vaccines

Cell Passage and Culture

Marc-145 cells, MDBK cells and BT cells which were used to culture the PRV vaccine strain Bartha K61, were trypsinized and passaged respectively in cell growth medium. The cells were cultured at 37° C. in culture medium. After the cells formed a single layer, they were passaged or inoculated respectively with a virus strain.

Propagation of the Seed Virus in Cells

The PRV vaccine strain Bartha K61 was inoculated to a single layer of Marc-145 cells, MDBK cells or BT cells in MEM medium containing 2-4% bovine serum. The inoculated cells were cultured respectively for 2-3 days, and the virus solutions were collected as the seed virus of PRV vaccine strain.

Characterization of the Seed Viruses

The seed viruses were characterized. The PRV seed viruses were tested as a qualified seed solution, and did not show adverse effects to pigs. The seed virus solution of PRV strain contained no less than 10^(8.0)TCID₅₀ virus per 1 ml.

Propagation of the Virus Solution of the PRV Vaccine Strain

The PRV stain was inoculated to a confluent single layer of Marc-145 cells, MDBK cells or BT cells at MOI of 0.005-0.5 with maintenance medium added. The inoculated cells were cultured at 36-37° C. and the virus solution was collected when CPE reached 70%.

The amount of the virus solution was measured after freeze-thaw for 2 cycles. The seed virus solution contained no less than 10^(8.0)TCID₅₀ virus per 1 ml. The virus solution was characterized in accordance with the Veterinary Pharmacopoeia of People's Republic of China, and was absent for bacteria, mold, or mycoplasma. The qualified virus solutions were stored under −15° C. and used as the virus solution for vaccine production. The virus solution was diluted appropriately to prepare PRV single vaccine, or mixed with other vaccines to prepare combined vaccines.

Example 4 Preparation of a Combined Vaccine Composition for PRRSV and CSFV

Antigen solution was prepared by combining the virus solution of PRRSV TJM strain (prepared according to Example 1) and the virus solution of CSFV C strain (F16) (prepared according to Example 2).

Heat-resistant cryoprotectant was prepared by mixing sucrose, L-sodium glutamate, and lactalbumin hydrolysate in a suitable ratio, followed by autoclave.

75-80 of volume fraction of the antigen solution was mixed with 25-20 of volume fraction of the cryoprotectant, and the mixture was filed into ampoules in a predetermined amount. The ampoules were capped and were subject to low temperature and drying process to get freeze-dried vaccine composition. The vaccine composition was tested for sterility, safety, and efficacy.

In each dose of the combined PRRSV and CSFV vaccine as prepared, the amount of PRRSV TJM strain was ≧10^(5.0)TCID₅₀, and the amount of CSFV C strain (F16) was ≧7500 RID (or ≧750 RID, or ≧150RID), or no less than 10^(4.0) FA-TCID₅₀ virus as measured by an immunofluorescence-based method.

The combined vaccine was characterized according to page 15, 19 and 20 of the appendix of Veterinary Pharmacopoeia of People's Republic of China. The combined vaccine was absent for bacteria, mold, mycoplasma and exogenous virus.

Example 5 Preparation of a Combined Vaccine Composition for PRRSV and PRV

Antigen solution was prepared by combining the virus solution of PRRSV TJM strain (prepared according to Example 1) and the virus solution of PRV Bartha K61 strain (prepared according to Example 3).

Heat-resistant cryoprotectant was prepared by mixing sucrose, L-sodium glutamate, and lactalbumin hydrolysate in a suitable ratio, followed by autoclave.

6-8 of volume fraction of the antigen solution was mixed with 2-4 of volume fraction of the cryoprotectant, and the mixture was filed into ampoules in a predetermined amount. The ampoules were capped and were subject to low temperature and drying process to get freeze-dried vaccine composition.

In each dose of the combined PRRSV and PRV vaccine as prepared, the amount of PRRSV TJM strain was ≧10^(5.0)TCID₅₀, and the amount of PRV Bartha K61 strain was ≧10^(5.5)TCID₅₀.

The combined vaccine was characterized according to page 15, 19 and 20 of the appendix of Veterinary Pharmacopoeia of People's Republic of China. The combined vaccine was absent for bacteria, mold, mycoplasma and exogenous virus.

Example 6 Preparation of a Combined Vaccine Composition for PRRSV, CSFV and PRV

Antigen solution was prepared by combining the virus solution of PRRSV TJM strain (prepared according to Example 1), the virus solution of CSFV C strain (F16) (prepared according to Example 2), and the virus solution of PRV Bartha K61 strain (prepared according to Example 3).

Heat-resistant cryoprotectant was prepared by mixing sucrose, L-sodium glutamate, and lactalbumin hydrolysate in a suitable ratio, followed by autoclave.

75-80 of volume fraction of the antigen solution was mixed with 25-20 of volume fraction of the cryoprotectant, and the mixture was filed into ampoules in a predetermined amount. The ampoules were freeze-dried to provide the vaccine composition. The vaccine composition was tested for sterility, safety, and efficacy.

In each dose of the combined PRRSV, CSFV and PRV vaccine as prepared, the amount of PRRSV TJM strain virus was ≧10^(5.0)TCID₅₀, the amount of CSFV C strain virus was ≧7500 RID (or ≧750 RID, ≧150 RID), or no less than 10^(4.0) FA-TCID₅₀ virus as measured by an immunofluorescence-based method and the amount of PRV Bartha K61 strain virus was ≧10^(5.5)TCID₅₀.

The combined vaccine was characterized according to page 15, 19 and 20 of the appendix of Veterinary Pharmacopoeia of People's Republic of China. The combined vaccine was absent for bacteria, mold, mycoplasma and exogenous virus.

Example 7

Gene Characterization of PRRSV TJM Strain

The PRRSV TJM strain contained in the virus solution as prepared according to Example 1, and in the combination vaccines as prepared according to Examples 4-6 was characterized by PCR, using primers specific to nsp2 of PRRSV (forward primer: 5′-GGCAAGAAGTTGAGGAAGT-3′; reverse primer: 5′-TGGCAGGTTGGTCACAGA-3′). PRRSV TJ strain was a positive control and water was a negative control.

The results showed a specific 207 bp band in the samples containing PRRSV TJM strain, as compared to a 567 bp band in the positive control containing PRRSV TJ strain (FIG. 5). The results confirmed that PRRSV TJM strain lacks 360 nucleotides in nsp2 gene, and further confirmed that the vaccines as prepared is not contaminated with PRRSV TJ strain.

Example 8 Gene Characterization of PRV Bartha K61 Strain

The PRV Bartha K61 strain contained in the virus solution as prepared according to Example 3, and in combination vaccine compositions as prepared according to Examples 5-6 was characterized by PCR, using primers specific to gE of PRV (forward primer: 5′-CGTCACGGTCACCAAGGAGC-3′; reverse primer: 5′-GCACAGCACGCAGAGCCAG-3′). PRV virulent strain (JL1 strain) was a positive control and water was a negative control.

According to the results, no band was found in the samples containing PRV Bartha K61 strain, as compared to a 232 bp band in PRV virulent strain (FIG. 6).

The results confirmed that PRV Bartha K61 strain contains deletion in gE gene, and further confirmed that the vaccines as prepared is not contaminated with PRV virulent strain.

Part II: Efficacy Studies

Example 9 Determination of Minimum Immunologically Effective Dose for PRRSV TJM Strain

25 healthy weaning pigs were used in the study. The pigs were negative for highly-pathogenic PRRSV, in terms of both antigen and antibody. The pigs were randomized in 5 groups. Group I to VI were inoculated with different doses of PRRSV TJM strain, while Group V was kept as negative control (Table 1). Pigs were challenged with virulent PRRSV TJ strain, and protection rates were calculated after the study. According to Table 1, PRRSV TJM strain at 10^(4.5) TCID50 or higher amount was sufficient to induce protective immunity in pigs, with a protection rate of 4/5.

TABLE 1 No. of No. of No. sick/ dead/ of Vaccination Virus challenge dosage/ No. of No. of Protection Group pigs dosage/pig pig tested tested rates I 5 10^(5.5) TCID₅₀ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 1/5 0/5 4/5 II 5 10^(4.5) TCID₅₀ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 1/5 0/5 4/5 III 5 10^(3.5) TCID₅₀ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 3/5 0/5 2/5 IV 5 10^(2.5) TCID₅₀ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 5/5 1/5 0/5 V 5 PBS 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 5/5 2/5 0/5

Example 10 Determination of Minimum Immunologically Effective Dose for CSFV C Strain (F16)

28 healthy weaning pigs were used in the study. The pigs were negative for CSFV, in terms of both antigen and antibody. The pigs were randomized in 6 groups. Group I to V were inoculated with different doses of CSFV C strain (F16), while Group VI was kept as negative control (Table 2). Pigs were challenged with virulent CSFV Shimen strain, and protection rates were calculated after the study. According to Table 2, CSFV C strain (F16) at 10^(0.5) TCID50 or higher amount was sufficient to induce protective immunity in pigs, with a protection rate of 5/5.

TABLE 2 No. Virus No. of No. of of Vaccination challenge sick/No. dead/No. Group pigs dosage/pig dosage/pig of tested of tested Protection rates I 5 10^(4.5) FA TCID₅₀ 10^(6.0) MLD 0/5 0/5 5/5 II 5 10^(3.5) FA TCID₅₀ 10^(6.0) MLD 0/5 0/5 5/5 III 5 10^(2.5) FA TCID₅₀ 10^(6.0) MLD 0/5 0/5 5/5 IV 5 10^(1.5) FA TCID₅₀ 10^(6.0) MLD 0/5 0/5 5/5 V 5 10^(0.5) FA TCID₅₀ 10^(6.0) MLD 0/5 0/5 5/5 VI 3 PBS 10^(6.0) MLD 3/3 3/3 0/3 MLD: Minimum lethal dose.

Example 11 Determination of Minimum Immunologically Effective Dose for Combined Vaccine of PRRSV TJM Strain and CSFV C Strain (F16)

40 healthy piglets were used in the study. The pigs were negative for both highly-pathogenic PRRSV and CSFV, in terms of both antigen and antibody. The pigs were randomized in 4 groups. Groups I to III groups were inoculated with different doses of the combined vaccines of PRRSV TJM strain and CSFV C strain (F16), while Group IV was kept as a negative control. Half of the pigs in each group were challenged with PRRSV TJ strain, and the other half were challenged with CSFV Shimen strain. Protection rates were calculated after the study.

According to Table 3, combined vaccine containing 10^(4.5) TCID50 of PRRSV TJM and 10^(3.5) FA-TCID50 of CSFV C strain (F16) was sufficient to induce protective immunity in pigs (Tables 3 and 4). In particular, CSFV C strain (F16) demonstrated 100% protection in all dosages as tested in the combined vaccine, indicating that the immune response to CSFV C strain (F16) was not suppressed by PRRSV TJM strain. Moreover, in view of the extremely low immunologically effective dosage of CSFV C strain (F16) as demonstrated in Example 10, lower dosages of CSFV C strain (F16) can be used in the combined vaccine without reducing the protection rate.

TABLE 3 No. PRRSV TJ No. of sick/ No. of dead/ of challenge No. of No. of Protection Group pigs Vaccination dosage/pig dosage/pig tested tested rates I 5 PRRSV TJM: 10^(5.5) TCID₅₀; 2 × 10^(4.0)-2 × 10^(4.5) 0/5 0/5 5/5 CSFV C strain (F16): 10^(4.5) TCID₅₀ FA-TCID₅₀ II 5 PRRSV TJM: 10^(4.5) TCID₅₀; 2 × 10^(4.0)-2 × 10^(4.5) 0/5 0/5 5/5 CSFV C strain (F16): 10^(3.5) TCID₅₀ FA-TCID₅₀ III 5 PRRSV TJM: 10^(3.5) TCID₅₀; 2 × 10^(4.0)-2 × 10^(4.5) 2/5 0/5 3/5 CSFV C strain (F16): 10^(2.5) TCID₅₀ FA-TCID₅₀ IV 5 PBS 2 × 10^(4.0)-2 × 10^(4.5) 5/5 4/5 0/5 TCID₅₀

TABLE 4 No. CSFV Shimen No. of sick/ No. of dead/ of challenge No. of No. of Protection Group pigs Vaccination dosage/pig dosage/pig tested tested rates I 5 PRRSV TJM: 10^(5.5) TCID₅₀; 10^(6.0) MLD 0/5 0/5 5/5 CSFV C strain (F16): 10^(4.5) FA-TCID₅₀ II 5 PRRSV TJM: 10^(4.5) TCID₅₀; 10^(6.0) MLD 0/5 0/5 5/5 CSFV C strain (F16): 10^(3.5) FA-TCID₅₀ III 5 PRRSV TJM: 10^(3.5) TCID₅₀; 10^(6.0) MLD 0/5 0/5 5/5 CSFV C strain (F16): 10^(2.5) FA-TCID₅₀ IV 5 PBS 10^(6.0) MLD 5/5 5/5 0/5

Example 12 Combined PRRSV TJM Strain and CSFV C Strain (F16) does not have Immuno-Inhibition

30 healthy pigs aged 21-28 days were used in the study. The pigs were negative for both highly-pathogenic PRRSV and CSFV, in terms of both antigen and antibody. The pigs were randomized in 7 groups, with 5 pigs in each of Groups I to V, 3 pigs in Group VI and 2 pigs in Group VII (Table 5). Each pig was inoculated with 1 ml of the testing sample, or not inoculated at all (i.e. Group VII), according to the study design shown in Table 5.

TABLE 5 No. of Group pigs Testing sample Amount Vaccine dose I 5 PRRSV TJM 1 ml 10^(5.0) TCID₅₀/ml II 5 CSFV C strain 1 ml 7500 RID/ml (F16) (or 10^(4.0) FA-TCID₅₀/ml) III 5 PRRSV TJM + 1 ml PRRSV: 10^(5.0) TCID₅₀/ml CSFV C strain CSFV: 7500RID (F16) (or 10^(4.0) FA-TCID₅₀/ml) IV 5 PRRSV TJM + 1 ml PRRSV: 10^(5.0) TCID₅₀/ml CSFV C strain CSFV: 7500RID (F16) (or 10^(4.0) FA-TCID₅₀/ml) V 5 PBS 1 ml N/A VI 3 PBS 1 ml N/A VII 2 N/A N/A N/A “RID”: rabbit infective dose; “N/A”: No inoculation or vaccination was performed.

Rectal temperatures of the pigs were taken each day from the 3^(rd) day before the vaccination until the 14^(th) day after the vaccination. Body weights were measured every 7 days. The pigs were also under close clinical observation. Blood samples were taken from each of the pigs in the study at the 3^(rd) day before the vaccination, the 0 day, 3^(rd) day, 7^(th) day, 10^(th) day, 14^(th) day, 21^(st) day, and 28^(th) day after the vaccination, respectively. Each blood sample was divided into two portions. One was treated with an anticoagulant, and was used for detection of CD3⁺, CD4⁺, CD8⁺ and CD4⁺ CD8⁺ T cells. The other portion was treated with a coagulant, and was used for antibody titer assay.

Results showed that the changes in CD3⁺, CD4⁺, CD8⁺ and CD4⁺CD8⁺ T cells in the vaccinated pigs were similar to those observed in the pigs of the control groups (FIGS. 7-10). After vaccination with the combined vaccines, pigs in Groups III and IV produced antibodies against both viruses, and such antibody productions did not interfere with each other (FIGS. 11-12). The kinetics of PRRSV antibody production for pigs in Groups III and IV was similar to those for pigs in Group I, and the kinetics for CSFV antibody production for pigs in Groups III and IV was similar to those for pigs in Group II. The results showed that, vaccination of PRRSV TJM strain does not inhibit the immunological response against CSFV C strain (F16), and vice versa.

The rectal temperatures and the body weights of the pigs in each group do not show significant difference (FIG. 13).

At the 28^(th) day after the vaccination, the pigs were challenged with virulent viruses, according to the study design shown in Table 6. After the virus challenge, rectal temperatures of the pigs were taken each day, and the pigs were observed for clinical manifestations including appetite, breathing, and spirits. Blood samples were taken from each of the pigs at the 0 day, 3^(rd) day, 7^(th) day, 10^(th) day, and 14^(th) day respectively, after the virus challenge, and were treated with an anticoagulant for detection of CD3⁺, CD4⁺, CD8⁺ and CD4⁺CD8⁺ T cells. Blood samples were also taken on the day of virus challenge and each other day after the challenge, for isolation of PRRSV virus and CSFV virus, and determination of presence of viremia. Clinical protection rates, morbidity (i.e. number of sick pigs/number of tested pigs), and mortality (i.e. number of dead pigs/number of tested pigs) were calculated for each group of animals 14 days after the virus challenge study, and the results are shown in Table 6.

TABLE 6 No. of dead/ Pig Challenge Challenge No. of sick/ No. of Protection Group No. sample dose/pig No. of tested tested Rate I 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) 0/5 0/5 5/5 TCID₅₀ II 5 CSFV 10^(6.0) MLD 0/5 0/5 5/5 Shimen III 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) 0/5 0/5 5/5 TCID₅₀ IV 5 CSFV 10^(6.0) MLD 0/5 0/5 5/5 Shimen V 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) 5/5 3/5 0/5 TCID₅₀ VI 3 CSFV 10^(6.0) MLD 3/3 3/3 0/3 Shimen VII 2 N/A N/A N/A N/A N/A “MLD”: minimum lethal dose; “N/A”: No inoculation or vaccination was performed.

Results showed that, after the virus challenge, body temperatures were elevated in non-vaccinated pigs of Groups V and VI, but not in vaccinated pigs of Groups I-IV (FIGS. 14-15). Pigs in Group V demonstrated clinical symptoms for highly-pathogenic PRRS such as low spirit, stress in breath, red skin, etc. Pigs in Group VI demonstrated significant symptoms for classical swine fever, including low spirit, constipation followed by diarrhea, red skin, etc. No pigs in the vaccinated groups demonstrated such clinical symptoms (FIGS. 16-17).

After the virus challenge, non-vaccinated pigs of Groups V and VI showed a significant drop in CD3⁺, CD4⁺, CD8⁺ and CD4⁺CD8⁺ T cells, and started to die from 7^(th) day after the virus challenge. On the other hand, pigs vaccinated with the combined vaccines or the single vaccines did not show such significant drop in T cells, and the T cell profiles were comparable to the healthy pigs in the blank control group. This indicated that the vaccines were effective in eliciting cellular immune responses. In addition, the pigs vaccinated with the combined vaccines and the pig with the single vaccines showed similar changes in CD3⁺, CD4⁺, CD8⁺ and CD4⁺CD8⁺ T cells, which indicated that the combined vaccines were free from immuno-inhibition against each other (FIGS. 18-25).

After challenge with highly virulent PRRSV, non-vaccinated pigs of Group V started to develop viremia from day 2, which lasted up to 11 days. However, pigs vaccinated with the combined vaccines or the PRRSV single vaccine did not develop viremia until day 4, which lasted up to 5 days. This indicated that the combined vaccines and the single vaccine both provided effective protection against infection of highly-pathogenic PRRSV, and the combined vaccines were free from immuno-inhibition against each other.

After challenge with virulent CSFV, all pigs in Group VI developed viremia, but none of the vaccinated pigs developed viremia. This indicated that the combined vaccines and the single vaccine both provided effective protection against infection of virulent CSFV, and the combined vaccines were free from immuno-inhibition against each other.

Example 13

Efficacy Study of the 2-Combo Vaccine for PRRSV and CSFV

Efficacy study was carried out using three batches of the lab-made 2-combo vaccine for PRRSV and CSFV (Batch No.: 200904, 200905, and 200906), prepared according to Example 4.

28 healthy pigs, negative for both highly virulent PRRSV and CSFV, in terms of both antigen and antibody, were used in the study for each batch of the 2-combo vaccine sample. The pigs were randomized in 6 groups, with 5 pigs in each of Groups I to IV and Group VI, and 3 pigs in Group V. Each group of pigs was inoculated with its respective testing sample, and at the 28^(th) day after the vaccination, the pigs were challenged with a virulent virus, in accordance with the study design shown in Table 7.

TABLE 7 Virus challenge and Protective rates Group Testing sample and dosage dosage/pig 200904 200905 200906 I 2-combo vaccine, 1 ml/pig: CSFV Shimen: 5/5 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(6.0) MLD CSFV C strain (F16) (7500 RID/ml, or 10^(4.0) FA-TCID₅₀/ml) II 2-combo vaccine, 1 ml/pig: PRRSV TJ, 4/5 4/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 2 × 10^(4.0)-2 × 10^(4.5) CSFV C strain (F16) (7500RID/ml, TCID₅₀ or 10^(4.0) FA-TCID₅₀/ml) III CSFV C strain (F16), 1 ml/pig: CSFV Shimen: 5/5 5/5 5/5 7500 RID/ml, or 10^(4.0) 10^(6.0) MLD FA-TCID₅₀/ml IV PRRSV TJM, 1 ml/pig: PRRSV TJ, 5/5 4/5 4/5 10^(5.0) TCID₅₀/ml 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ V PBS, 1 ml/pig CSFV Shimen: 0/3 0/3 0/3 10^(6.0) MLD VI PBS, 1 ml/pig PRRSV TJ, 0/5 0/5 0/5 2 × 10^(4.0)-2 × 10^(4.5) TCID_(5.0) “RID”: rabbit infective dose; “MLD”: minimum lethal dose;

The CSFV virus challenge study ended at the 16^(th) day after the challenge, and the PRRSV virus challenge study ended at the 21^(st) day after the challenge. The protection rates were calculated and the results are shown in Table 7. All of the three batches of the 2-combo vaccines of PRRSV and CSFV demonstrated good protection against the challenge from highly virulent PRRSV or CSFV. The protection from the 2-combo vaccine showed no significant difference from the single vaccine controls. The un-vaccinated pigs all showed evident clinical symptoms of infection.

Example 14 Immuno-Duration Study of the 2-Combo Vaccine for PRRSV and CSFV

Immuno-duration study was carried out using the 2-combo vaccine for PRRSV and CSFV (as prepared according to Example 4). PRRSV single vaccine (as prepared according to Example 1) and CSFV single vaccine (as prepared according to Example 2) were used as controls.

56 healthy pigs were used in the immuno-duration study. All pigs were negative for PRRSV and CSFV, in terms of both antigen and antibody. The pigs were randomized into 6 groups, and were inoculated with the respective testing samples as shown in Table 8. Blood samples were collected for determination of antibody titers at 1st, 2nd, 3rd, 4th, 5th, or 6th months post vaccination.

At the 3rd and the 6th month post vaccination, respectively, half of the animals were taken from each study group. These animals were challenged with the respective virulent virus, as shown in Table 8.

Results showed that (see Table 8), the 2-combo vaccines provided effective protection to pigs against virus challenge 6 months after the vaccination, and therefore supported a 6-month immuno-duration period. The immuno-duration of the 2-combo vaccine was found comparable to that of the single vaccines.

TABLE 8 Virus challenge and dosage/ Protective rates Group Vaccine inoculation and dosage pig 3-mon 6-mon I 2-combo vaccine, 1 ml/pig: CSFV Shimen strain 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(6.0) MLD CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) II 2-combo vaccine, 1 ml/pig: PRRSV TJ strain, 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) III CSFV C strain (F16), 1 ml/pig: CSFV Shimen strain 5/5 5/5 7500 RID, or 10^(4.0) FA-TCID₅₀/ml 10^(6.0) MLD IV PRRSV TJM, 1 ml/pig: PRRSV TJ strain, 4/5 4/5 10^(5.0) TCID₅₀/ml 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ V PBS, 1 ml/pig: CSFV Shimen strain 0/3 0/3 10^(6.0) MLD VI PBS, 1 ml/pig: PRRSV TJ strain, 0/5 0/5 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ “RID”: rabbit infective dose; “MLD”: minimum lethal dose;

Example 15 Combined PRRSV TJM Strain and PRV Bartha K61 Strain does not have Immuno-Inhibition

2-combo vaccine for PRRSV TJM and PRV Bartha K61 (prepared according to Example 5) was used in the study. Pigs aged 4-5 weeks were randomized in 4 groups, with 4 pigs in each group. All pigs were negative for PRRSV and PRV, in terms of both antigen and antibody.

Pigs were inoculated with the respective testing sample, according to the study design shown in Table 9. The second vaccination was performed one week after the first vaccination.

TABLE 9 Group First vaccination Second vaccination I PRRSV TJM, 1 ml/pig: PRV Bartha K61, 1 ml: 10^(5.0) TCID₅₀/ml 10^(5.5) TCID₅₀/ml II N/A 2-combo vaccine, 1 ml: PRRSV TJM (10^(5.0) TCID₅₀/ml) + PRV Bartha K61(10^(5.5) TCID₅₀/ml) III N/A PRV Bartha K61, 1 ml (10^(5.5) TCID₅₀/ml) IV N/A PBS “N/A”: No inoculation or vaccination was performed.

After the vaccination, blood samples of the pigs were collected each week, until the 28^(th) day after the vaccination. The blood samples were treated and detected for antibody titers against PRV.

Results showed that (FIG. 26), the PRV antibody titer was not significantly different among Groups I to III. This suggested that PRRSV TJM strain did not have immuno-inhibition against the PRV vaccine. PRRSV TJM strain did not affect the PRV antibody titer when administered separately or as a combined vaccine with PRV. The 2-combo vaccine for PRRSV and PRV had an efficacy comparable to that of a PRV single vaccine.

Example 16 Efficacy Study of the Combined PRRSV and PRV Vaccine

Efficacy study was carried out using three batches of the 2-combo vaccines for PRRSV and PRV, prepared according to Example 5.

Pigs aged 4-5 weeks were randomized into 4 groups, with 10 pigs in each group. Groups I to III were injected with one dose of a respective batch of 2-combo vaccine. Each dose of the vaccine contained 10⁵⁰TCID₅₀/ml PRRSV TJM strain and 10^(5.5)TCID₅₀/ml PRV Bartha K61 strain. Group IV was a control group and was injected with 1 ml MEM medium.

After the vaccination, the pigs were observed for clinical manifestations and adverse effects. The blood of the pigs was collected each week, and serum was separated for characterization of the antibody titers. The body weight of the pigs was measured every week.

4 weeks after the vaccination, 5 pigs in each group were challenged with PRRSV TJ strain at a dose of 2×10^(4.0)-2×10^(4.5) TCID₅₀, and the other 5 pigs were challenged with PRV virulent strain (JL1 strain) at a dose of 10^(3.0)-10^(3.5) TCID₅₀. After the virus challenge, the pigs were observed for clinical manifestations including appetite and spirit. Rectal temperatures of the pigs were taken each day. Blood samples and nasal swabs were collected for virus characterization.

Results showed that, vaccinated pigs in Groups I to III showed normal temperature and were in good spirits and good appetites after vaccination. After the virus challenge, the vaccinated pigs were protected with a protective rate of above 4/5, while all of the non-vaccinated pigs in the control group developed infection, and had a mortality rate of 2/5 from virulent PRRSV challenge and 3/5 from virulent PRV challenge. The results suggested that the 2-combo vaccine for PRRSV and PRV had good efficacy against the challenge of both viruses, and were effective in preventing infection of PRRSV and PRV.

Example 17 Combined PRRSV TJM Strain, CSFV C Strain and PRV Bartha K61 Strain does not have Immuno-Inhibition

46 healthy pigs aged 21-28 days were used in the study. The pigs were negative for highly virulent PRRSV, CSFV and PRV, in terms of both antigen and antibody. The pigs were randomized into 10 groups, with 5 pigs in each of Groups I to VII and Group IX, and 3 pigs in each of Groups VIII and X. The pigs were inoculated with 1 ml of the testing sample as assigned, or not inoculated at all (i.e. Group X), according to the study design shown in Table 10.

TABLE 10 No. of Group pigs Testing sample Vaccine dose I 5 PRRSV TJM, 1 ml/pig 10^(5.0) TCID₅₀/ml II 5 CSFV C strain (F16), 7500 RID/ml 1 ml/pig (or 10^(4.0) FA-TCID₅₀/ml) III 5 PRV Bartha K61, 1 ml/pig 10^(5.5) TCID₅₀/ml IV 5 3-combo vaccine, 1 ml/pig: PRRSV: 10^(5.0) TCID₅₀/ml PRRSV TJM + CSFV: 7500 RID/ml CSFV C strain (F16) + (or 10^(4.0) FA-TCID₅₀/ml) PRV Bartha K61 PRV: 10^(5.5) TCID₅₀/ml V 5 3-combo vaccine, 1 ml/pig: PRRSV: 10^(5.0) TCID₅₀/ml PRRSV TJM + CSFV: 7500 RID/ml CSFV C strain (F16) + (or 10^(4.0) FA-TCID₅₀/ml) PRV Bartha K61 PRV: 10^(5.5) TCID₅₀/ml VI 5 3-combo vaccine, 1 ml/pig: PRRSV: 10^(5.0) TCID₅₀/ml PRRSV TJM + CSFV: 7500 RID/ml CSFV C strain (F16) + (or 10^(4.0) FA-TCID₅₀/ml) PRV Bartha K61 PRV: 10^(5.5) TCID₅₀/ml VII 5 PBS, 1 ml/pig N/A VIII 3 PBS, 1 ml/pig N/A IX 5 PBS, 1 ml/pig N/A X 3 N/A N/A “RID”: rabbit infective dose. “N/A”: No inoculation or vaccination was performed.

Rectal temperatures of the pigs were taken each day from the 3^(rd) day before the vaccination until the 7^(th) day after the vaccination. The pigs were also under close clinical observation. Blood samples were taken from each of the pigs in the study at the 3^(rd) day before the vaccination, the 0 day, 3^(rd) day, 7^(th) day, 10^(th) day, 14^(th) day, 21^(st) day, 28^(th) day, 31^(st) day, 35^(th) day, 38^(th) day, and 42^(nd) day after the vaccination, respectively. Each blood sample was divided into two portions. One was treated with an anticoagulant, and was used for detection of CD3⁺, CD4⁺, and CD8⁺ T cell detection. The other portion was treated with a coagulant, and was used for antibody titer assay.

At the 28^(th) day after the vaccination, the pigs were challenged with virulent viruses, according to the study design shown in Table 11. After the virus challenge, rectal temperatures of the pigs were taken each day, and the pigs were observed for clinical manifestations including appetite, breathing, and spirits. The PRRSV challenge study ended at 21^(st) day after the virus challenge, and the CSFV challenge study ended at the 16^(th) day after the virus challenge. Clinical protection rates, morbidity (i.e. number of sick pigs/number of tested pigs), and mortality (i.e. number of dead pigs/number of tested pigs) were calculated for each group after the virus challenge study, and the results are shown in Table 11.

TABLE 11 No. of No. of Pig Challenge sick/No. dead/ No. Protection Group No. sample Challenge dose/pig of tested of tested Rate I 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 0/5 0/5 5/5 II 5 CSFV Shimen 10^(6.0) MLD 0/5 0/5 5/5 III 5 PRV JL1 10^(3.0)-10^(3.5) TCID₅₀ 0/5 0/5 5/5 IV 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 0/5 0/5 5/5 V 5 CSFV Shimen 10^(6.0) MLD 0/5 0/5 5/5 VI 5 PRV JL1 10^(3.0)-10^(3.5) TCID₅₀ 0/5 0/5 5/5 VII 5 PRRSV TJ 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ 5/5 3/5 0/5 VIII 3 CSFV Shimen 10^(6.0) MLD 3/3 3/3 0/3 IX 5 PRV JL1 10^(3.0)-10^(3.5) TCID₅₀ 5/5 5/5 0/5 X 3 N/A N/A N/A N/A N/A “MLD”: minimum lethal dose; “N/A”: No inoculation or vaccination was performed.

Results showed that PRRSV TJM strain, when combined with the CSFV C strain and the PRV Bartha K61 strain, provided effective protection against challenge of all three virulent viruses. The combined vaccines showed comparable efficacy to that of each single vaccines, suggesting that the combined vaccines were free from immuno-inhibition against each other.

Example 18 Efficacy Study for Combined PRRSV TJM Strain, CSFV C Strain and PRV Bartha K61 Strain

Efficacy study was carried out using three batches of the lab-made 3-combo vaccine (batch No.: 031-01, 031-02, and 031-03), prepared according to Example 6.

43 healthy pigs, negative for highly virulent PRRSV, CSFV and PRV, in terms of both antigen and antibody, were used in the study. The pigs were randomized in 9 groups, with 5 pigs in each of Groups I to VI, Group VIII and Group IX, and 3 pigs in Group VII. Each group of pigs was inoculated with its respective testing sample, and at the 28^(th) day after the vaccination, the pigs were challenged with a respective virulent virus, in accordance with the study design shown in Table 12. The PRRSV challenge study ended at 21^(st) day after the virus challenge, the CSFV challenge study ended at the 16^(th) day after the virus challenge, and the PRV challenge study ended at the 14^(th) day after the virus challenge. Clinical protective rates, morbidity, and mortality were calculated for each group of animals after the virus challenge study, and the results were shown in Table 12.

TABLE 12 Protective rates Virus challenge Batch Batch Batch Group Vaccine inoculation and dosage and dosage/pig No. 1 No. 2 No. 3 I 3-combo vaccine, 1 ml/pig: CSFV Shimen: 5/5 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(6.0) MLD CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) II 3-combo vaccine, 1 ml/pig: PRRSV TJ, 4/5 4/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 2 × 10^(4.0)-2 × 10^(4.5) CSFV C strain (F16) (7500 RID, or 10^(4.0) TCID₅₀ FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) III 3-combo vaccine, 1 ml/pig: PRV JL1: 5/5 4/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(3.0)-10^(3.5) TCID₅₀ CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) IV CSFV C strain (F16), 1 ml/pig: CSFV Shimen: 5/5 5/5 5/5 7500 RID, or 10^(4.0) FA-TCID₅₀/ml 10^(6.0) MLD V PRRSV TJM, 1 ml/pig: PRRSV TJ, 5/5 4/5 4/5 10^(5.0) TCID₅₀/ml 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ VI PRV Bartha K61, 1 ml/pig: PRV JL1: 4/5 4/5 5/5 10^(5.5) TCID₅₀/ml 10^(3.0)-10^(3.5) TCID₅₀ VII PBS, 1 ml/pig CSFV Shimen: 0/3 0/3 0/3 10^(6.0) MLD VIII PBS, 1 ml/pig PRRSV TJ, 0/5 0/5 0/5 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ IX PBS, 1 ml/pig PRV JL1: 0/5 0/5 0/5 10^(3.0)-10^(3.5) TCID₅₀ “RID”: rabbit infective dose; “MLD”: minimum lethal dose;

The three batches of the 3-combo vaccines of PRRSV, CSFV and PRV all demonstrated good protection against challenge from highly virulent PRRSV, CSFV or PRV, while the negative controls all showed evident clinical symptoms of infection. The protection from the 3-combo vaccine showed no significant difference from the single vaccine controls.

Example 19 Immuno-Duration Study for Combined PRRSV TJM Strain, CSFV C Strain and PRV Bartha K61 Strain

Immuno-duration study was carried out using three batches of the lab-made 3-combo vaccine (batch No.: 031-01, 031-02, and 031-03), prepared according to Example 6.

86 healthy pigs were used in the immuno-duration study. The pigs were negative for highly virulent PRRSV, CSFV and PRV, in terms of both antigen and antibody. The pigs were randomized into 9 groups, with 6 pigs in Group VII, and 10 pigs in each of the remaining groups. The pigs received vaccination or nothing according to the study design shown in Table 13. Blood samples were collected for determination of antibody titers at 1^(st), 2^(nd), 3^(rd), 4^(th), 5^(th), or 6^(th) month post vaccination.

At 3 months and 6 months post vaccination, respectively, half of the animals were taken from each study group and were challenged with the respective virulent virus, as shown in Table 13.

TABLE 13 Virus challenge and Protective rates Group Vaccine inoculation and dosage dosage/pig 3-mon 6-mon I 3-combo vaccine, 1 ml/pig: CSFV Shimen: 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(6.0) MLD CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) II 3-combo vaccine, 1 ml/pig: PRRSV TJ, 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 2 × 10^(4.0)-2 × 10^(4.5) CSFV C strain (F16) (7500 RID, or 10^(4.0) TCID₅₀ FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) III 3-combo vaccine, 1 ml/pig: PRV JL1: 5/5 5/5 PRRSV TJM (10^(5.0) TCID₅₀/ml) + 10^(3.0)-10^(3.5) TCID₅₀ CSFV C strain (F16) (7500 RID, or 10^(4.0) FA-TCID₅₀/ml) + PRV Bartha K61 (10^(5.5) TCID₅₀/ml) IV CSFV C strain (F16), 1 ml/pig: CSFV Shimen: 5/5 5/5 7500 RID, or 10^(4.0) FA-TCID₅₀/ml 10^(6.0) MLD V PRRSV TJM, 1 ml/pig: PRRSV TJ, 4/5 4/5 10^(5.0) TCID₅₀/ml 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ VI PRV Bartha K61, 1 ml/pig: PRV JL1: 4/5 4/5 10^(5.5) TCID₅₀/ml 10^(3.0)-10^(3.5) TCID₅₀ VII PBS, 1 ml/pig CSFV Shimen: 0/3 0/3 10^(6.0) MLD VIII PBS, 1 ml/pig PRRSV TJ, 0/5 0/5 2 × 10^(4.0)-2 × 10^(4.5) TCID₅₀ IX PBS, 1 ml/pig PRV JL1: 0/5 0/5 10^(3.0)-10^(3.5) TCID₅₀ “RID”: rabbit infective dose; “MLD”: minimum lethal dose;

Results showed that (see Table 13), the 3-combo vaccines provided effective protection to pigs against virus challenge 6 months after the vaccination, and therefore supported a 6-month immuno-duration period. The immuno-duration of the 3-combo vaccines was found comparable to each of the single vaccines.

Part III: Safety Studies

Example 20 Safety Study of the Combined PRRSV and CSFV Vaccine

Safety study was carried out using three batches of the lab-made 2-combo vaccine for PRRSV and CSFV (batch No.: 200904, 200905, and 200906), as prepared according to Example 4.

The study included a single dose safety study, repetitive dose safety study, over-dose safety study on target age pigs, over-dose safety study on under-age pigs, and over-dose safety study on pigs of different breeds.

The results showed, after vaccination, pigs in each study group showed normal temperature, were in good spirits and good appetites. No systemic or local adverse effects were observed. Over-dose administration of the combination vaccines was shown to be safe to under-age pigs, and also to pigs of different breeds.

Example 21 Safety Study of the Combined PRRSV and PRV Vaccine

Safety study was carried out using three batches of the 2-combo vaccine of PRRSV and PRV, as prepared according to Example 5.

Pigs aged 4-5 weeks, negative for both PRRS and PR, in terms of both antigen and antibody, were randomized in 3 groups, with 15 pigs in each group. Each group was inoculated with the 2-combo vaccine in a single dose (10^(5.0)-10^(5.5)TCID₅₀ virus/ml), repetitive doses or a 10-fold over-dose. 5 pigs were used as a control group and were not inoculated at all.

Rectal temperatures of the pigs were taken each day, until the 21^(st) day after the vaccination. The pigs were also under close clinical observation.

The results showed that pigs in each group showed normal temperature and no pathological changes after vaccination. The 2-combo vaccine was safe to pigs.

Example 22 Safety Study of the Combined PRRSV, CSFV and PRV Vaccine

Safety study was carried out using three batches of the lab-made 3-combo vaccine for PRRSV, CSFV and PRV (batch No.: 031-01, 031-02, and 031-03), as prepared according to Example 6. The study included a single dose safety study, repetitive dose safety study, over-dose safety study on target age pigs, over-dose safety study on under-age pigs, and over-dose safety study on pigs of different breeds.

The results showed, after vaccination, pigs in each study group showed normal temperature, were in good spirits and good appetites. No systemic or local adverse effects were observed. Over-dose administration of the combination vaccine was shown to be safe to under-age pigs, and also to pigs of different breeds.

Part IV: Stability Studies

Example 23 Stability Study of the 2-Combo Vaccine for PRRSV and CSFV

The lab-made combined PRRSV and CSFV vaccines (batch Nos.: 200904, 200905, and 200906) were tested for stability, and compared in parallel with three batches of PRRSV single vaccine and CSFV single vaccine (batch Nos.: 200901, 200902, 200903, 200907, 200908, and 200909).

The three batches of each of the vaccine composition were kept at 2-8° C. Samples were collected at 3, 6, 9, 12, and 18 months of the study, respectively. The samples were tested for physiochemical properties, vacuum degree, residual water content, potency, and aging at 37° C.

After 18-month storage at 2-8° C., the three batches of the 2-combo vaccine compositions were in white loosen clumps, which were rapidly dissolved upon addition of a diluting buffer. In the test of degree of vacuum, the vaccines showed white or purple glow. The average residual water content of the tested vaccines met the requirements set by Chinese Veterinary Pharmacopoeia.

The virus titers of the vaccine compositions were determined, and the results were shown in FIGS. 27-30. After storage at 2-8° C. for 18 months, the virus titers of the 2-combo vaccine were not significantly different from that of each single vaccine. After being kept at 37° C. for 14 days, the 2-combo vaccines still contained high level of virus titers, which were not significantly different from each of the single vaccine in the parallel studies. The virus titers of the vaccine compositions met the requirement for a qualified vaccine. This showed that the heat-resistant cryoprotectant provided good protection to the PRRSV vaccine strain and the CSFV vaccine strain during the freeze-drying procedures.

As is known in the art, conventional vaccines are usually kept under 0° C. (−20° C.), which complicates the storage of the vaccines. The results of this Example showed that, with the new cryoprotectant, the vaccine compositions can be shipped and stored at a higher temperature, thereby providing a higher stability of the vaccines.

Example 24 Stability Study of the 2-Combo Vaccine for PRRSV and PRV

The three batches of lab-made 2-combo vaccines for PRRSV and PRV were kept at 2-8° C. Samples were collected at 3rd, 6th, 9th, 12th, 18th, 21st and 24th months of the study, respectively. The samples were tested for physiochemical properties, vacuum degree, residual water content, potency, and aging at 37° C.

After 24-month storage at 2-8° C., the three batches of the vaccine compositions were in white loosen clumps, which were rapidly dissolved upon addition of a diluting buffer. In the test of degree of vacuum, the vaccines showed white or purple glow. The virus titers of the vaccine compositions were determined, and the results were shown in FIGS. 31-34. The combined vaccines were stable after storage at 2-8° C. for 24 months, and the virus titers were not significantly different from those before the storage.

Example 25 Stability Study of the 3-Combo Vaccine for PRRSV, CSFV and PRV

The lab-made 3-combo vaccines for PRRSV, CSFV and PRV (batch Nos.: 031-01, 031-02, and 031-03) were tested for stability, and compared in parallel with three batches of PRRSV single vaccine (batch Nos.: 031-04, 031-05, 031-06), CSFV single vaccine (batch Nos.: 031-07, 031-08, 031-09) and PRV single vaccine (batch Nos.: 031-10, 031-11 and 031-12).

The vaccine compositions were kept at 2-8° C. Samples were collected at the 3rd, 6th, 9th, 12th, and 18th month of the study, respectively. The samples were tested for physiochemical properties, vacuum degree, residual water content, potency, and aging at 37° C.

After 18-month storage at 2-8° C., the three batches of the vaccine compositions were in white loosen clumps, which were rapidly dissolved upon addition of a diluting buffer. In the test of degree of vacuum, the vaccines showed white or purple glow. The average residual water content of the tested vaccines met the requirements set by Chinese Veterinary Pharmacopoeia.

The virus titers of the vaccine compositions were determined, and the results were shown in FIGS. 35-40. After storage at 2-8° C. for 18 months, the virus titers of the combined vaccines were not significantly different from that of the single vaccines. After being kept at 37° C. for 14 days, the combined vaccines still showed high level of virus titer, which was not significantly different from that of the single vaccines under the parallel studies. This demonstrated that, the heat-resistant cryoprotectant provided good protection to the PRRSV vaccine strain, the CSFV vaccine strain and the PRV vaccine strain during the freeze-drying procedures. 

1. A vaccine composition, comprising a Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) vaccine and a second porcine virus vaccine, wherein the PRRSV vaccine and the second vaccine are substantially free from immuno-inhibition against each other.
 2. The vaccine composition of claim 1, further comprising a third porcine virus vaccine, wherein the PRRSV vaccine, the second vaccine and the third vaccine are substantially free from immuno-inhibition against each other.
 3. The vaccine composition of claim 1, wherein the second porcine virus vaccine is selected from Classical Swine Fever Virus (CSFV) vaccine and Pseudorabies Virus (PRV) vaccine.
 4. The vaccine composition of claim 2, wherein the third porcine virus vaccine is selected from Classical Swine Fever Virus (CSFV) vaccine and Pseudorabies Virus (PRV) vaccine, and wherein the third vaccine is different from the second vaccine.
 5. The vaccine composition of claim 1, wherein the PRRSV vaccine comprises an attenuated PRRSV.
 6. The vaccine composition of claim 5, wherein the attenuated PRRSV comprises an Nsp2 nucleotide encoded by a DNA sequence which, when compared with SEQ ID NO: 4, lacks a DNA fragment comprising at least 50 contiguous nucleotides, wherein the DNA fragment is at least about 80% homologous to an equal length portion of SEQ ID NO:
 8. 7-9. (canceled)
 10. The vaccine composition of claim 5, wherein the attenuated PRRSV comprises an Nsp2 nucleotide encoding for a Nsp2 protein sequence which, when compared with SEQ ID NO: 11, lacks a peptide fragment comprising at least 20 contiguous amino acids, wherein the fragment is at least about 80% homologous to an equal length portion of SEQ ID NO:
 9. 11-13. (canceled)
 14. The vaccine composition of claim 5, wherein the attenuated PRRSV is attenuated from a highly-pathogenic PRRSV. 15-19. (canceled)
 20. The vaccine composition of claim 1, wherein the attenuated PRRSV comprises a PRRSV nucleotide sequence encoded by a sequence having at least 90% homology to SEQ ID NO:
 3. 21-22. (canceled)
 23. The vaccine composition of claim 3, wherein the CSFV vaccine comprises an attenuated CSFV. 24-26. (canceled)
 27. The vaccine composition of claim 3, wherein the PRV vaccine comprises an attenuated PRV. 28-31. (canceled)
 32. The vaccine composition of claim 1, wherein the vaccine composition provided herein comprises an immunologically effective amount of the PRRSV vaccine, the CSFV vaccine and/or the PRV vaccine.
 33. The vaccine composition of claim 32, wherein the immunologically effective amount of the PRRSV vaccine is at least 10^(4.5) TCID₅₀, 10^(5.0) TCID₅₀, or 10^(5.5) TCID₅₀, the immunologically effective amount of the CSFV vaccine is at least 10^(0.5) FA-TCID₅₀ (fluorescent antibody—TCID₅₀), 10^(1.0) FA-TCID₅₀, 10^(1.5) FA-TCID₅₀, 10^(2.0) FA-TCID₅₀, 10^(2.5) FA-TCID₅₀, 10^(3.0) TCID₅₀, 10^(3.5) FA-TCID₅₀, 10^(4.0) FA-TCID₅₀, 10^(40.5) FA-TCID₅₀, or 10^(5.0) FA-TCID₅₀, or is at least 2.5 RID, 3 RID, 5 RID, 10 RID, 30 RID, 100 RID, 150RID, 300 RID, 750RID, 1000 RID, 3000 RID, or 7500 RID, and/or the immunologically effective amount of the PRV vaccine is at least 10^(3.0) TCID₅₀, 10^(3.5)TCID₅₀, 10^(4.0)TCID₅₀, 10^(4.5) TCID₅₀, 10^(5.0) TCID₅₀, 10^(5.5) TCID₅₀ or 10^(6.0) TCID₅₀.
 34. The vaccine composition of claim 32, wherein the TCID₅₀ ratio of the PRRSV vaccine to the CSFV vaccine ranges from 10000:1 to 1:1.
 35. The vaccine composition of claim 32, wherein the TCID₅₀ ratio of the PRRSV vaccine to the PRV vaccine ranges from 1:1 to 1:30.
 36. The vaccine composition of claim 32, wherein the TCID₅₀ ratio of the PRRSV vaccine:the CSFV vaccine:the PRV vaccine ranges from about 10⁴:1:10⁵ to about 5:1:6. 37-39. (canceled)
 40. A method for preparing the vaccine composition of claim 2, comprising: (a) collecting PRRSV vaccine strain, CSFV vaccine strain and/or PRV vaccine strain, which are cultivated in their respective susceptible cells, and (b) mixing two or more of the virus strains at a suitable TCID₅₀ ratio. 41-51. (canceled)
 52. A method for preventing or treating Porcine Reproductive and Respiratory Syndrome, Classical Swine Fever, and/or Pseudorabies comprising: administering the vaccine composition of claim 1 to a subject.
 53. A method of immunizing a pig, comprising administering to the pig the vaccine composition of claim
 1. 54. A CSFV vaccine strain, cultured in a cell line selected from the group consisting of ST, PK-15, Marc-145, MDBK, BT, PT, Vero, BHK-21, porcine kidney cell line (IBRS-2), rabbit kidney cell line (RK), and chicken embryo fibroblast cell line, or a primary cell which is porcine kidney primary cells.
 55. (canceled) 